What Causes Severe Nerve Pain In Lower Back, Left Hip And Leg?

I had a fusion in my L/4-5 (lower spine) in 1989. Since then I was left with severe nerve pain in lower back, left hip and left leg. The pain managers Have been giving me selective nerve root injections and methadone for pain. The nerve pain is always there. When it reaches a 10 pluse I feel like I want to die lately. The last pain management doctor I started with in 2006 intill recently gave me several nerve blocks constantly, which I always had a reaction in my face swelling and blood vessels breaking in face. When I started seeing him 8 yrs ago I was in 240mg methadone daily for pain. A yr ago I decreased dose to 120mg daily. At first I could handle for couple of months. Then I really pushed myself to try and exercise more instead of just physical therapy and stretches everyday. My nerve pain got so severe that I have been laying on right side 24/7 with ice packs. I been to emergency twice. My last MRI was in 2010. I m getting an updated one on 2/20/15. I m trying to find a new comprehensive program to understand what can be done. Do you have any suggestions and/or thoughts? It s been 15 yrs now and I m desperate. I live in El Dorado County, CA area. I was going to try Sutter Hospital in Sacramento, but I m just not sure. Thanks for your time! Now you want $ for an answer. This sounds like another scam. SHAME On YOU!