I was recently diagnosed with PCOS. It sounds similar to what you are experiencing. YOu should get the doctor to check your hormone levels.
If you have not had sex, you are not pregnant. See your doctor if the cramping and pain continues.
Oh and i has on bc for a while due to health concerns. My periods used to be really bad. They would last two weeks and i would bleed heavily every day and i would only have a teo week brseak before my next period would hit. I stoppdd taking it awhile ago though