Masturbating

Okay, so recently I've just started masturbating. I've done it before but I've never orgasmed and when I started doing it again, I just started orgasming. Now I know how to make myself orgasm pretty much every time I masturbate. I maybe masturbate once or twice each night and every time I do, my stomach starts to hurt. It's nauseating like I want to throw up and it's similar to cramps. Does anyone else have this problem? Please help!