My Raya cat goes through periods where she doesn't seem to eat much of her food, and will throw it up right after eating. I am not sure if she is gorging or the food is upsetting her stomach. I read where sometimes cats will get gastritis, but not sure what causes it. Maybe I should change her food. She is (well, both cats but Pandora doesn't have an issue) currently getting Royal Canin dry urinary food mixed with IAMS dry urinary food and every other day they get a can of Friskies shreds. I know that the Royal Canin urinary is just mostly filler, so maybe I should feed a good dry mixed with the IAMS urinary. Suggestions?