Help for lower back pain?

I have extreme back pain that seems to be getting progressively worse. I have been to several doctors and have had X-rays, Bone scan, MRI scans with and without contrast and a EMG test. The EMG shows I have a pinched nerve at L5/S1. All the MRI's and x-rays show everything as normal except L5 has a fracture which I'm told is generic and is not my problem since the bone is still aligned. Also I have a 15 degree curvature in my back which has been there since childhood and has not increased. Physical therapy greatly increases the pain, laying down and sitting down hurt as well as heavy lifting. I do have pain going into my legs and tingling sensation at times but not always. The MRI does not show any slipped disk or growths. The pain is a bit greater on my right side then my left. I did have an accident on a snowmobile when I was younger which hurt my back but that pain went away and then I didn't really have back trouble till 3 or 4 years later when I started working. Sorry this is so long but my doctor says he has no further ideas on what is wrong and wants me to try Physical therapy again but I already spent more then a year in therapy and also tried chiropractor but both make my pain worse. Hope that someone out there could give me some advice or have an idea what is wrong. Thank you in advance for your answers.