It might be in his best interest just to switch back to the clumping litter. If he is holding it and going to the bathroom at the last minute possible because he doesn’t like it, it will just make him sick which will end up being another Vet visit.
My best advice to give you is to watch him with an eagle eye. Keep adding H2O to his food and figure out a way to make some flavored H2O out of ingredients that you feel good feeding him. Maybe the litter (I’ve never used it) clumps differently, more compact, than clay litter also making it appear smaller.
Trust your gut, take him to the Vet if you feel it is necessary. Catching a UTI early is the best for both of you.
What’s the temp where you live?
