It could be so many things, including sciatica. (the low back and leg pain.) There is no reason for anyone to live with chronic pain. Keep getting opinions from various kinds of doctors, until you obtain the right diagnosis.
I had to see over 60 doctors. I've horrible chronic optic nerve pain. I saw specailists from coast to coast. Opthalmologists, acupuncture, chiropractic, neurologists, you name it! Finally all decided drug therapy was the only method to go, So I'm totally hooked on MSContin and Fiorinal w/Codeine, but I can laugh and revel in my family. It's well worth it in my experience.
Good luck to you. Don't quit! Get at least three opinions from ob/gyns. Get referrals towards the best. Good luck to you, my pal. 