Doesn't sound at all like FIP. The big bellies are full of fluid, and there is no pain from it. They are usually happy at first, then appetite fails, then the hiding starts. At that point vet does tap, finds viscous yellow fluid in abdomen, and that pus history is diagnostic. Dry FIP is different, they cycle in and out of feeling better and feeling worse, eating and not eating, and eventually they stay in feeling worse and not eating. Also, there is NO TEST for FIP1 They can test for the corona virus but a positive test doesn't mean positive for FIP, because corona virus mutates to become FIP but doesn't do that in all cats. Your cat sounds like mine who had megacolon, and eventually he ended up having pumpkin in his food all the time and that kept things moving. (Prior to that, he had to go through the enemas in the vet hospital to unblock him, because he was pretty much blocked and bloated when we got him into rescue.) Your cat sounds exactly like that one.
