Cat won't pee, not blocked

My indoor cat got out on Saturday.  He was gone for less than 24 hours.  The short story is that he was acting very cranky about 12 hours after he came home, growling, unhappy, not drinking.  Off to the vet on Sunday.  Vet thinks he is fine, may have pulled some muscles, mildly dehydrated, runs blood work, gives sub cutaneous fluids and pain meds.

Monday evening I get a call that the blood work is back and they are concerned.  There are protein markers in the urine that are very high that indicate "severe muscle trauma".  Vet says he likely was kicked or fell from somewhere.  His bladder is very distended, he has been blocked before.  They catheterize him - he isn't blocked this time just won't pee.  Vet thinks possibly because it hurts to squat.  More sub cutaneous fluids, more pain meds.  

It is important that he drinks and eats so that his body can flush out these proteins otherwise they could basically clog his kidneys and cause renal failure.  He is eating and drinking - actually ate all of his wet food tonight which not normal.

I still don't think he is peeing.  He is a previously obese cat so he has a nice dangley tummy but it fees like I can feel his bladder in there.  He seems otherwise quite happy, grooming himself and being mostly normal.

His white blood cell count was also up so he is on antibiotics.

I am not sure what to do.  I don't want to run back to the vet to have him catheterized again but I am concerned.  He doesn't seem distressed and isn't even trying to pee.

Is there any other reason a can't won't pee besides a blockage.  Maybe he has a bladder infection and it hurts to pee? I am at a loss.  

Ok we have pee.  He is spending a lot of time cleaning himself.  I think maybe he does have a bladder infection.  

I am relieved that he has relieved himself

If he does have a bladder infection, then the antibiotics should take care of it.  Did the vet do a urine culture?

I always add water to my kitties' wet food just to make sure they get enough water.  You might try offering wet food that's had a couple of teaspoons of water added and see if he likes it. 

No urine culture was done. His white blood cells were elevated enough that the vet thought he had an infection but we didn't know where. We couldn't find any evidence of bites or abceses. Vet gave Rumble an antobiotic injection. So it is possible it could be a bladder infection. All we know for certain is that he is not blocked.

Rumble likes running water so this has been a little difficult. I think he is too sore to support himself on the tub like he usually does. He does like it when my daughter brings him a container of water and he takes his sweet time drinking so she has been his nursemaid.

His brother also escaped at the same time and he brought back friends so now we have to treat all cats in the house for fleas (we have 6, my daughter's and mine). This has turned into a very expensive little adventure.

I hope Rumble has learned his lesson, this is why we don't go outside.