Hello and thanks, The symptoms may be due to many reasons. The first is endometrioma as it comes and goes and you have history of endometriosis. It is rare but possible. Check to see if its appearance has any relation to menstruation. Other possibilities are a hernia, lipoma, hemangioma and so on. They are all soft and may be painful. Hernia is a prolapse of abdominal contents mostly intestine or omentum from a small defect or hole in the abdomen coverings. Lipomas and hemangiomas are non cancerous tumors of different tissues. So you need an examination as description cannot pin point the diagnosis. You may also need an ultrasound. So get examined and evaluated for final diagnosis and treatment. Hope this satisfies your query. Thanks for using HCM. Feel free to ask any more questions that you may have. Dr Madhuri Bagde Consultant Obstetrician and Gynecologist