I have two sibling cats who are 2 years old. They are Siamese/Tabby. They vomit almost daily. Should I be concerned? They have been fed Science diet since they were kittens. I bought them a raised food dish, and that seemed to help some. The vomit is almost always whole food, with the occasional hairball. They are free fed. Their weight is good, they are very active, have beautiful coats and drink plenty of water. Is this something that warrants a trip to the vet?