This has been happening for about 4 years now, and I've had my period for about 8 years. About a week (sometimes 2 weeks) before my period is meant to begin, I get these piercing cramps/pains that last for about 15 minutes per hour. They're so bad that I can't sleep for more than an hour at once.

I don't know whether this is normal or not, and if not, what could it be? If it is, what can I do to lessen the pain? I am not sexually active, nor have I ever been, so please don't say that I might be pregnant.