Anti-inflammatories. Nsaids (or anti-inflammatory) meds are helpful for 'period cramps'. They block a chemical 'prostaglandin' thought to mediate the pain of your cramps. Examples of nsaids are aleve (take 2, 2 x/day) or Motrin (may need 3-4 @ a time up to 3 times/day). Severe 'cramps' also can be helped by 'the pill'/oral contraceptive. Please get a check-up to rule out other causes including 'endometriosis'.
Don't forget veins. Venous insufficiency and varicose veins is a very common cause of leg cramps. If you have trouble with leg cramps and have veins you can see in your legs, I would recommend seeing a phlebologist (vein specialist).