I have been having the same kind of pain that you have been experiencing for 6 months. The exact point of my pain is about an inch to the right of the spine at the L4-L-5 level. I had an mri and the conclusion was a small protruding disc at the L4-5 level with minor neural foraminal narrowing. I have had pelvic/abdominal cat scans, as well as many ultrasounds. The only thing that has been found is the protruding disc. I have done pt and it helped a little, but I am worried that there could be something more going on. Did your pain show up after an accident or just out of the blue? Have you gone to a doctor yet?
I would go to my primary care physician and get some test run. ERs can only do so much. If you don't have a pcp maybe someone will refer you to a good one? I'm not a doctor, but it sounds serious enough to me that I would get it checked out. So many things it could be. Good luck.