I.G.
Yeah, not to scare you but you should not take this lightly. It can be anything from irritation/inflamation due to torsion/adhesions from surgery to cancer.
I had symptoms like you described after an appendectomy at age 14. I needed an exploratory laparoscopy and it turned out that I had a chronic inflammation of the ovaries and uterus due to the adhesions from the earlier surgery. Once they clipped the scar tissue I was fine and they did not come back.
Good luck!