Agree with Lili. Prostaglandin levels can be a major contributor to cramps. If you suffer from severe cramps you can attend at your local well woman clinic and ask to be tested. Nonsteroidal anti-inflammatories (NSAIDS)such as Ibuprofen can help lower Prostaglandins.
When I first hit menarche, I used to get terrible cramps and was often excused netball (which was a bummer cos I really loved netty), but I'd go to see the nurse and she had the classic "indisposed" couch in the treatment room. It helped, but a warm water bottle was additional relief. Nurse was against using medication unless it was really needed, so I figure my pain didn't reach her threshold for tablets. lol.
Exercise in the days leading up to your period is also good. It helps lower the prostaglandin level so a brisk daily walk for twenty minutes or so, in the last few days
before can help a lot.
I don't get cramps so much these days, but when I do, I stretch out for a while with a warm water bottle on my tum and this helps.
.