Throwing up, and hunger pains?!

This has only been happening for three days now, but at random times i get hunger pains and so I eat quick things to feel me up, but then almost immediately i feel nauseous and sometimes i throw up but i've only threw up today and yesterday but still. I'm a 16 year old female, and please no "your pregnant" answers because i'm still a Virgin... unless you know something I don't know? Anyway i'm thinking about going to the doctors but they'll just say "oh your pregnant" when I know i'm not. I'm not under any stress because my life's going good at the moment, my grandma thinks it might be because I don't eat a lot, and I don't eat healthy food, is she right? I don't eat as much as a normal 16 year old girl should, but this is ridiculous please help?