Hi, It may be caused by ovarian cysts which are in most cases small and asymptomatic and it means that it doesn’t cause any significant symptoms and doesn’t require specific treatment. However, in cases or cysts larger than 5 cm, bleeding cysts, torsion or rupture surgical treatment is required. Also, if there is polycystic syndrome as underlying cause then hormonal therapy is indicated. Pain is usually placed deep in pelvis on affected side and may be associated with nausea and fever. To diagnose it you should do ultrasound and vaginal examination. I hope I have answered you query. If you have any further questions you can contact us in every time. Wish you a good health. Kind regards, Dr. Ivan R. Rommstein