I'm taking Ortho tri Cyclen. The pill is known to reduce the number of days you have your period, the flow amount and the pain. I was originally put on the pill as a teenager to help with the pain because I'd always have to leave school cause the pain was so bad I'd be vomiting. Are you on anything like the pill, IUD, shot etc.?
Other methods that can help with pain are hot water bottles (which also apply a little pressure), heating pad, eating chocolate (cocoa is a know natural pain killer) etc. I'd also suggest a trip to your OBGYN to get things checked out and make sure everything is all right in there. For me its normal for my period to make my Crohn's symptoms worse but if you are noticing that its been A LOT worse the past few months then you should have a doctor check it out for sure.