My cat Sonny has thrown up food every few days since he was a kitten, now he is 14. Somtimes he just eats too fast, but other times it is because of his oversensitive intestines. I try to feed him little amounts at a time so it doesn't bother his intestinal walls too much. A friend of mine also has this problem with her cat. If everything else is ruled out it could just be this and then I wouldn't worry. Once I got Sonny a feline leukemia shot and it seemed to help for a while and then it wore off. We know now that it was not feline luek, but it was worth a try to find out if that was the problem. If he has always done this without any other health problems I'd just say its the intestinal walls, I don't know if anything can be done about that or not.