Hi: I have three cats and one of my cats has been throwing up at least once a day for a couple days now. Not sure if I should be worried. Can you help? He is a Persian and 1 1/2 yrs. old. He is not throwing up hairballs, he is throwing up food. I haven't changed anything in his diet and don't know why he's throwing up. Can you give me any insight???? THANK YOU!!!