I used to get extreme cramps and would lay curled up into a ball with pain, feeling sick etc. The doctor prescribed Anaprox which you can now find at the drugstore by the name of Aleve. The generic name is naproxen sodium. Maybe that will help you feel better, I couldn't really go without it on some days. The dosage I was taking was a little stronger than sold in the stores, but not much. You may need three if two don't help.
The gynecologists I went to didn't seem to think it was unusual for some women, so can't give you an explanation for mine, but the pain comes from uterine contractions. You should see an OBGYN or GYN for problems related to that area and get a checkup/pap smear once a year. You can ask them if there is any other reason for those severe cramps, there could be, or they may just be something you have to live with like I did. Some months were worse than others I noticed and I only took the pills on the days I needed them. They last for 12 hrs so may help you sleep through the night.
Here is a link with some other tips:
http://womenshealth.about.com/cs/crampsmenstrual/ht/menstrualcramps.htm
Endimitious(spelled wrong) Are you on any birth control? cause that is suppose to help it.