Suggest Remedy For Painful Menstrual Cramps

First, I should start off saying that I am 353lbs. About 2 weeks ago, I went in for my yearly physical (Pap, Pregnancy Test, etc). Before this last visit, it had been 2 years since having a physical done. While I did not have a physical for 2 years, I also was not on any type of birth control. My periods were very irregular, but I did not experience severe menstrual cramps. At my last physical I was put back on birth control (Ortho). I have not missed a day taking them, but a few days after starting the Green pills, I started to have very painful menstrual cramps. The severe pain started yesterday, and it is not constant. One minute the pain, on a scale of 1-10, is about a 2 or 3. The next minute, the pain is about an 8 or 9. Most of the pain is in my lower back, but whenever the 8-9 pain comes, it spreads to my thighs and lower front. I am trying to determine whether or not I need to go to the doctor, but I'm not sure when to know. Please help. Thanks.