This sounds like something I had a few months ago. Is it like a stomach pain or like intense menstrual cramps? Mine where like intense menstrual cramps but I wasn't having my period. I had an ultrasound and they found I have cysts in my uterus. I'm on birth control pills now and all the pain has stopped. BCP are good for a lot of other things besides birth control Since you had an ultra sound and they didn't find cysts, then I guess it's something else. The symptoms seemed so similar though.

Prayers and hugs are on the way!