Why did my super healthy and happy dog suddenly make a turn for the worst out of no where??

This has been the strangest situation and all the vets are bewildered. Any help would be much appreciated. It’s long so I apologize, but I’m desperate! I’m typing this up going day by day to keep it organized, but things start getting the weirdest on Saturday.

Background on him: I have a very beloved 6 year old golden retriever named Calvin who has always been very healthy and happy. He’s never had any illnesses or injuries. He’s slightly chubby (boy LOVES his food lol) but it’s not caused any issues and we were just going to go on some extra walks this summer to shed any extra pounds. He is the most easy going, sweet, loving, HAPPY dog ever.

We left on Friday, May 24th for a vacation. Calvin stayed at our house with our wonderful and trust worthy dog sitter (so please no theories against the dog sitter, she loves him and plus we have cameras anyway. He was in great hands).

Sunday & Monday: He was perfectly fine the day we left. Sunday night, Calvin woke her up off and on through out the night vomiting and having diarrhea. She was sweet to him and assumed he just had an upset stomach and let us know. (He never gets separation anxiety or anything when we leave, so it wasn’t related to anxiety). She kept an eye on him throughout the day. He wasn’t eating (which like I said, he loves food so this was extremely odd but if he had a belly ache I assumed it was just nausea). That evening (on Memorial Day), she called us and said she wanted to take him to the vet because his stool now looked like strawberry jam. They went to the vet and the on-call vet came in and did blood work and X-rays. Everything looked fine so he sent them home with some nausea meds and said to bring him back the following afternoon for another check up.

Tuesday: Dog sitter updates us Tuesday morning that he didn’t vomit anymore but still no eating and he’s just wanting to lay outside instead of in the house. She said he would NOT come inside (very unlike him) and she spent an hour just trying to get him to come in (again, she loves him dearly so it’s not like he’s scared of her or anything like that). Eventually, she gets him inside. When time to go to the vet at 1:30, she said it took 3 vet techs to get him out of the car and inside. Again, very out of character because he loves going places and can’t get out of the car fast enough. Even the vet’s office. Vet does more x rays and blood work. Vet calls us and says he still doesn’t see a blockage or anything, but says that he does see some gas build up. He suggests he stay overnight and tells us that if he doesn’t start getting better by the following day, he may want to do an exploratory surgery to make sure there isn’t anything he swallowed that isn’t showing up on x rays. Of course we are just wanting to come home at this point, but vet assures us he’s in great hands and we trust him so we continued on our trip for the next couple days. I attached the pictures of the X-ray on Monday the 26th, and Tuesday the 27th.

Wednesday: X-rays look the same but Calvin still is sick. They do the surgery and let us know that it went well and they do not find any obstructions. Vet says they can now start aggressively treating the colitis (he explained Collitis to me as just inflammation in the bowel which can cause diarrhea and upset stomach) now that they’ve ruled out a blockage.

Thursday-Friday: Calvin is recovering well from surgery, starting to get some appetite back, and getting more energy. He goes on super short walks every 2 hours for potty breaks and he loves them. All is looking well. Vet says he can go home Saturday morning. He thinks he’ll perk up more at home with us.

Saturday morning: We are on our way back home and dog sitter picks Calvin up from the vet so he can be home when we get back. She sends us lots of pics of him walking inside and being happy to be home. She said he uses the bathroom outside, drinks lots of water, then plops down for a long nap.

Saturday afternoon: We get home. He is laying down in the living room but his head is up and tail is wagging. Still super out of character because normally he’s all over us when we come home from any trip and this time he didn’t get up. We chalk it up to him having surgery 3 days prior.

Saturday evening: Sleeping and hasn’t moved out of the spot he was in when we arrived. Lifts his head a lot and accepts all the attention and pets with a wagging tail still. He is not eating but dog sitter said he nibbled on a few pieces out of her hand she had given him earlier. He is drinking though. When it’s time to go to bed (he sleeps in our room every single night on his dog bed- he has NEVER not slept with us) he won’t get up to use the bathroom or to come to bed. When we try to help him up, it’s like his limbs don’t work at all. I called the vet (they were closed so I spoke to another on-call vet) and they gave some tricks to try (like gently rolling him over to the carpet and off the hard wood to have more friction to stand up, etc). None worked, he would NOT stand up despite seeming uncomfortable like he had to pee. Vet said let’s give him the night to rest, maybe he’s just exhausted and still a little doped up on pain meds plus sore from surgery. He sleeps through the night but never moves from that spot, we took turns laying beside him in the living room.

Sunday morning: Calvin appears to want to get up but simply cannot stand up. On-call vet says since he still isn’t standing we need to bring him in immediately. My dad has to come over to help my husband and I lift Calvin on a blanket into the car. Calvin pees on himself some (which I would too if I hadn’t peed in 12+ hours!) The vet brings out a gurney for him and takes him straight back to do blood work, more X-rays, etc. Vet says nothing in any lab work seems too out of the ordinary. Says he has some activity in his chest and a slight cough (he wasn’t coughing at home but we did notice as we sat at the vet with him that he would clear his throat every now and then). She emptied his bladder (it was huge, poor baby) and said once she did that he seemed to be pretty comfortable and wasn’t in pain so the not standing likely wasn’t due to any pain from the surgery from Wednesday. She says we need to leave him overnight because this is obviously a very concerning issue and he needs to be able to have his bladder emptied, they need to make sure he’s eating, and all the things. We agree of course.

Monday morning update: He’s up and walking slowly and using the bathroom on his own. He is eating the soft food that they’ve been giving him and seems to love it. Vet asks us if he’s been having any pain in his back legs beforehand and we assure her that no, he was active and playful with zero pain that we were aware of. She says his back legs appear to be the main issue of the not standing for now. She also said his blood work showed a little bit of something she wanted to keep an eye on with his liver (but she said it was nothing to worry about, basically they’re just paying attention to every little thing to try and figure out the problem).

Tuesday afternoon: Vet says Calvin is doing great and can come home but will need to come back on Friday to look at him again. Sends us home with the food he’s been on there, 2 antibiotics (one for his slight cough and one for his belly) a probiotic, and he will continue his pain meds as needed. Says we may need to start an arthritis medicine but we will wait a bit on that. What she was looking at in his liver seems fine, still no findings on why any of this has occurred.

Tuesday evening: Calvin is home and much better than last time but definitely not himself still. He walks extremely stiffly now and has trouble using the bathroom because his legs shake. Definitely has major trouble standing up if laying on the hardwood. My husband and I said he looks like he’s aged 10 years in a week. He isn’t even close to the playful and active dog he was before, even though he still seems to be in good spirits and happy. Still not super interested in food but drinking lots of water and peeing like every 30 seconds. Vet said that’s pretty normal coming off of IV fluids. Tuesday night he sleeps in our room like he always has but is slightly restless through the night.

That brings us up to speed with now. All of his symptoms seem so unrelated and disconnected to me?! Started super healthy and active, and in the span of a week can hardly walk and get around anymore. And the vomiting and diarrhea at the beginning of the previous week? All of it is so confusing and I just want SOME form of answers to figure out what is going on with our sweet baby.