How To Treat Chronic Back Pain Post L4-L5 Fusion Surgery?

Hi, doctor,I had back surgery L4-L5 fusion about 6 years ago, and still have extreme chronic pain. I take soma daily for relief which is minimal. my regular doctor prescribed me Norco which was effective, but the side effects were intolerable, as much as my extreme chronic pain is, so I decided to try to live with the pain. I am no longer with this doctor, and was recommended to see a pain management doctor or go to a pain relief specialist. what is the deference?which would be the