10 months no period, HORRIBLE cramping today

Hi all - I haven't had a period since last November. For the past 3-4 weeks I've had a lot of breast tenderness that felt much like old PMS symptoms. For the past 24 hours I've had horrible, awful cramps. Some nausea too but I think that's from the pain - and actually, it was never unusual for me to feel nauseous when I had bad cramping. Pregnancy not a concern. Ibuprofen helped me sleep a little last night but still didn't totally remove the pain. I'm guessing this may be either a period about to start, or at least my body trying to have a period. I'm pretty miserable though. Wondered other experiences? TY!