Why do I have cramps when I'm not suppose to get my period until the 27th?

I'm stressing out. I have monster cramps like when I'm on my period, but I don't have my period. I only had a little bleeding yesterday and I think it's because my boyfriend cut me a little yesterday. I'm just freaking out MAJORLY because I don't want to be pregnant. It could just be stress, I have had about four state regents that I've had to take in the past week. please help..