I had a hard mass in my lower pelvic area for about 12 months. I would get inflamed during my periods and the bloating was horrible. I finally asked for a lap and an umbilical hernia fix, as I was having such pain around my belly button around my period as well. Both by OB and General Surgeon agreed to tag team my surgery. I had a walnut size endo tumor grow through my abdominal wall. They removed it put in a mesh liner and stitched me up. I had no hernia in my belly button it was all pelvic cavity endo. I had a CT scan which didn't show any endo. I would go with your gut or get a second opinion.