I'm a vegetarian and I accidentally ate a piece of meat?!?

I have a terrible phobia of throwing up, and since I've been vegetarian for 2 eyars now, I might throw up from eating meat. Soo, I took a laxative to hopefully flush it out of my system before it goes...up instead of out back..whe can I expect the laxative to kick in?And what can I expect? Like, diarreah or stomach pains?