Because he was running into the litter box a lot when he was in distress last time, I'd keep on the lookout for that. Because it was an infection and not crystals, it is less likely that he'd be blocked. Every kitty we've had that was blocked let us know there was a problem - by constantly straining to pee. If he doesn't look like he's in discomfort, I'd just keep an eye on him to the extent possible.
I know it's really scarey to think about the potential toxicity of the urine killing him in a day or two if he's blocked - but if you were blocked and you couldn't pee - what would you be doing after 24 hours? Someone would be able to tell there's a problem! You wouldn't be making dinner, doing the laundry, or going to work like normal. You would be in too much discomfort. Keeping an eye on the litter box is a good idea - but with more than one cat, it's more important to keep an eye on the cat.
So your kitty normally eats dry food, not wet food? And the vet gave you prescription wet food? Are you putting out prescription dry food too?
See - cats digestive systems are pre-programmed to eat like your kitty was. Lots of teeney meals frequently. That's the problem (in my mind) with an only wet food diet - you can't leave the food out for them to nibble on the way they normally do.
If he's eating little bits, I guess just keep feeding it to him. I am almost positive the baby food wouldn't be a problem - but maybe our vet has a different opinion on this than yours, or maybe there's something about his infection I just don't know.
Plain chicken - boiled plain or as baby food with no additives - is pretty universally considered plain, neutral food for a cat that isn't allergic to it (and most aren't).
It was just that when our cats had to go on the prescription diet, we badgered the vet - NOTHING but the food? NO TREATS of any kind? No shrimp? No chicken? Not even baby food? He laughed - and said plain chicken or baby food - veal, beef or chicken for our crew - would make a good treat replacement. We divide up one jar between the six of them once every other day as a treat - and we mix a little bit of warm water into it.