What's wrong with my moms friend, doctors can't figure it out?

She still has a light period, no pain, her stomach is hard and there is a bulge That moves. Its been going on since labor day. They have done ultra sounds, cat scans and mri. All tests have come bavk negative. she's been through 3 doctors and no doctor knows anything.. please help her.
What's wrong with my moms friend, doctors can't figure it out?
Post Opinion