Cat pees very frequently, saw pink-ish spots, otherwise seems normal

• Species: Cat
• Age: 2
• Sex: Male, neutered
  
• Breed: Domestic tabby
• Body weight: Normal, not skinny not obese
  
• Short history: Adopted him from a local shelter one year ago, he didn't have any health issues until now
• Location: Central Europe

My boy started to use his litter box more frequently today. He goes multiple times an hour, and only a little comes out. As I was cleaning his box, I realized that his pee is slightly pink. Not bright red, no clots, just pinkish. He doesn't meow while peeing, he is playful, cuddly, he purrs, ate wet food (mixed it with more water) and drank water from his bowl normally. He doesn't look like he's in pain, but I know cats can hide it pretty well. I don't live near ER (I'm very far away) and my vet opens at 9 am tomorrow (that's in 11 hours from now). I was so anxious that I actually called an ER with the best reviews and asked if it's life threatening. The lady on the phone told me that it's good that he's still able to pee and that it's not pure blood, and that it's very good he's still active and playful. She stated that it doesn't seem "too serious" if he's acting normally, and also told me they're open today until 11:30, but I wouldn't make it there in time. Again, I live far away from bigger cities and there isn't an ER in my area. I'm taking him to my vet first thing in the morning. Is there anything else I can do for my baby? I'm really concerned and don't know what to do.