Should I be worried?

My period is usually every 35 days but I have cramping prior to the actual onset. About every two months I have insanely bad cramps; pain-relievers don't help at all to the point where I end up shaking in a cold sweat and alternating between hot and cold. My gynocologist put me on birth control pills and said that it should help but I kinda felt like she though I was just being a wimp. Does anyone else have this problem???