If you'll take ibuprofen, that often helps with cramps. Besides being an analgesic, it imitates certain prostaglandins and actually helps step back the cramping a bit. Bed and a heating pad or hot water bottle always helps me feel better too.

If you don't want to take ibuprofen, then Evening Primrose Oil replaces prostaglandins too. It never worked as well for me as a couple of Advil, though.