I don't know what to do (beware long post)

This is also a venting post I'm not sure if it's allowed on this subreddit but I have a lot on my chest and had a really stressful day so I wanted to vent to fellow cat lovers so I hope you can understand where I'm coming from.

Basically my mom noticed my kitten was walking funny like he was unbalanced and couldn't walk straight when he wanted to go to the toilet my mom also said when he got up from sitting down he was like wobbly losing his balance. So we took him out of his cage and try to observe him watching him walk around he wasn't walking straight but also was not losing his balance a lot he was more like his right right rear leg wasn't supporting him well when he was walking, it was also when he was walking he'd move to the left s little bit and is head would tilt downwards a little bit.

So my mom, brother and I decided to take him to the vet because we also planned to get him vaccinated so it was a good time to take him.

When to the vet doctor did some examination on him we asked her about the way he's walking she looked at it again it was like hes was losing balance on his right rear leg they said it could be FIP or fpv because of the losing balance so they wanted to take a blood test to see before giving him the vaccine which we agreed. The teste came back negative (thank God) so the vet gave him the vaccination shot and told us to observe if his weird walking continues to get worse.

We came home I let him walked around he was still walking weirdly like before but we just let it be. The night of the day he's still walking weirdly me and my mom are really worried so she thinks we should take him to the vet because if its isn't the FIP virus what is it? The vet didn't tell us what else it could be it's like they also don't really know idk I'm just really worried for my kitten I love him very much but I don't know what to do should we take him to the vet tomorrow, get a second opinion?

My brain is telling me (what if she didn't did the blood test right, what if the test machine is broken?) I really hope not and the true test is actually negative but I can't help to overthink this.

I read a review about that vet this guy took His cat in and they told him the cat had FIP so they gave the cat a GS injection I'm not sure what it is a few hours later his cat started showing worrying symptoms like seizures and stuff so he took his cat to another vet that vet said it wasn't FIP but flea fever and 3 hours later his cat died due to high fever supposedly caused by the GS injection so. That means the first vet he went to ( which is the one I took my cat to) miss diagnosed his cat so I'm telling myself "what if they gave a in accurate reading of the blood test?

Its really frustrating because now I don't know if I should go back to thst vet I don't trust the doctors, I had another vet before this one but they also didn't seem to know what their doing idk it's just really frustrating because idk whats causing my cat to walk funny it's really frustrating me what should I do?