You need to see your gynecologist. I too in my later yrs, now post menopausal, had cramps, due to using tampons, which prevented the easy flow of blood to be excreted from the body. Also, if I knew when my period was going to start, I would take an aspirin which acts as a blood thinner, between using Always Pads, I know it's not fun, and taking aspirin several times a day, should help you. Aspirin, Advil, or anything like it. Actually, Tylenol doesn't work the same way. At 44 and after having 3 children C-Section and was bleeding 3 out of 4 weeks, no pain at that point, but working for a Dr. was just darn inconvenient having to leave my desk every hr or so. I requested a hysterectomy, and haven't regretted it one iota. Sounds like you may not have children yet. Have you spoke with your family dr. or gyn?