I have not read any clear evidence about this. Orgasm causes your brain to release some feel-good chemicals that might actually have a relaxing effect on your body and your mood. In that respect, I would agree that masturbating might help with your period cramps as muscle tension and anxiety can certainly make your period cramps worse. So, I guess my answer to your question is going to be if it feels right, go for it. If not, here are some other ways that you can get some period relief: take a warm bath, take a nap, go for a walk, do relaxation exercises, laugh, drink plenty of water and get three servings of dairy each day.
This is a good question; one I wish I knew the answer to. Seems like masturbating would be a quick-fix solution for cramps. Maybe it could be your way of helping reduce the pain from cramps. For me, I like to fill up a water bottle, warm it up in the microwave, and then hold it against my stomach. To each their own. If it helps with cramps, then it’s like the Holy Grail, because all of us women know how much cramps can hurt and how epic the cure for them can be.