We were giving my cat a hairball remedy food (regular Purina)but then we switched to a better quality (Purina ONE). Then it got pricey all of a sudden so we switched back. My cat started throwing up every day. She would fill up on water and throw up clear water and hair. We switched back after trying another brand and she seems fine now but she lost a lot of weight in those two months before we got her re-adjusted to the Purina ONE. How can I get her to regain some weight so she isn't so bony? I tried giving her soft food but I find that I have to ration it because she just loves it so she sucks it back too fast and then...throws up. Then she won't also eat her dry food because she is waiting for her "fix".