Maybe just give the vet a call and let him know abotu Butter's behaviour. He justmight be really exhausted having been through a lot, and without food.

They had a catheter in for a while, so he might be dehydrated - it might be a bit before he builds up enough extra fluid to pee.

See what the vet says...I can't see ANY cat getting it again this soon. Just call the vet, hon, for a consult. He can tell you what to check for.