Why does cocaine make your stomach hurt?

My friend tried some cocaine yesterday and she really liked it, I wouldn't do any with her because I've seen what it does to people and I couldn't talk her out of it. She didn't do very much, I guess like 6 little lines. She did some more today, she said only 3 this time but now her stomach hurts?! Obviously she shouldn't do stupid drugs. Is it the cocaine that made it hurt? I licked just a little because she said it makes you feel numb like oral gel but it tasted really gross and my tounge was only numb for like 15 minutes so I'm guessing it wasn't very pure? Idk much about drugs.