P.G.
I had chronic lower back pain after my 2 youngest boys were born. I tried going to a Chiropracter (sp?) and she actually made it worse. I asked my Family Dr. if physical therapy might be helpful since medication wasn't helping. She said maybe, so guess what!? PT worked wonders!! If nothing else is wrong medically it would be worth trying.
I realize that my experience is not what you are dealing with, but the chronic pain after such a long time sounds to me like it is possibly muscular. Good luck!!