I bet it is Giardia. He had it last fall and was treated by the vet but may have got it again. I think I need to take him to the vet again. I'd hate to lose Luke - I'm very attached to him. I have to put a roof on their outdoor enclosure and hopefully it will keep most pathogens from my cats. My older, bigger cat Pete seems unaffected by it. He's a hardier cat for some reason, better genes or something.