Have you had any abdominal surgeries? If so could be nerve entrapment or damage. Unfortunately, I have the latter and haven't worked in 14 years.
I have also read that you can get bone spurs in your pelvis.
I would try and get ultra sound done of pelvic area.
Not trying to be negative Nelly here,. Just wanted to give couple options of what it could be. May need to find a pain clinic also. Some things are very hard to diagnosis, so maybe you can something for pain, since most docs won't prescribe anything that's going to help.
Let me know what you find out.
Take care of yourself, you know your own body and may take a couple docs to find one you feel comfy with.
Carol