When I got my Tuffy he had worms real bad with just horrible diarea and his little butt was all red and hurt something awfull, he was treated for the worms and that got better, but then he had to go on antibiotics for a long time to get rid of a bad URI and the antibiotics gave him bad diarea and his little butt got so sore again he also cried out when I would try and clean him up.
He finally got in pretty good shape for a couple months then he started to bleed sometimes after using the litter box, the vets thought at first it was IBD or IBS, we tried all kinds of things with him but nothing helped much, turned out he was developing FIP and he was gone in about 3 months after the bleeding from his rectum started. I was and still am totaly heart broken over loosing Tuffy only after having him a little over a year, he was a real sick stray when he came up to me while we were camping and I gave him something to eat and he stayed with us the whole weekend and he came home with us. They think he was only about 4 years old when he died. He was my little best friend, and a very special little guy.
Sorry to go on so long about this but reading about the IBS stuff reminded me about how they at first thought Tuffy had it when he started to have problems. I also have a bad case of IBS, mine is always bad diarea not constipation. I alway have to have imodium with the gas relief stuff with me on long car rides or I need to know where there is a bathroom close if I go anywhere. It will hit me right out of the blue sometimes and if there is no bathroom close I am in trouble,
and the bloating and cramping can be just terribly painfull. Sorry to get way off track here, I am sure others with IBS know what I am saying.