you could take a pain pill before going out, or wear those muscle heating pads that self heat i think you can get them at walmart they are for backs and legs/knees but the back one i turn it around onto the front.
usually exercise helps cramping but i personally never thought it helped hehe i just try stay on the couch during that time.
For some reason a banana always helps me, but I learned from one of my gym teachers in the past that working out can help with cramps on your period. But from my experience, a banana and some midol always helps!
Magnesium supplement. Lol. I always say this but it works. Drink a fizzy magnesium pill just before running. Also make sure you are hydrated. Then you can also take a pain pill before hand, that'll also work.
try taking a hot bath before you go out to run. this always helps