Why are my menstral cramps so terrible?!?

SOMETIMES my mesntral cramps are light as well as the flow. My periods are not regular yet. Im 17. Lately, the cramps have been so bad Im unable to move, or when I lie down I can't sit still and I get sick like fever, sometimes even throwing up. Why is that they get so bad? Also, is there a way to eat certain foods to reduce the flow and the cramps so they are not so bad? I cannot take anymore of this pain.