okay so it sounds like you are doing a lot of the physical htings you need to do. i know from personal experience that back/nerve pain can be mentally and emotionally taxing, i commend you for reaching out and encourage you to keep fighting for answers. remember, you are loved.
the one thing i did that relieved more pain than anything else was very simple: fasting. this is the most ancient and most powerful healing technique in the world. fasting supercharges the detox process, soothes muscles and nerves, calms inflammation, and centers the mind. fasting did more to allieviate my back pain than anything, including pain meds. fasting is a technique that has been preached and practiced by every holy man, avatar, prophet, and hard core health practitioner in history. Jesus Christ in Mattew said that some demons only come out "through prayer and fasting." i can't say it will work as well for you as it did for me as far as pain management, but i can tell you that it will revitalize your body and renew your spiritual life.
if you can't go completely without try a fresh juice fast, just drink organic apple/carrot/lemeon juice, delicious! or try an herbal tea fast (alfalfa, lemon grass, nettles, and comfrey are good nerve tonics) sweetened with mollases or fructose. start just one day a week. move on from there. what do you have to lose?
also as far as those who say your prayers aren't answered because of unbelief/posssesion? i say get away from them now!! they are not helping you heal, they are vampiring the energy necessary to jump start your healing process. God answers all prayers, it just may not be on our timetable. God loves us all, every one of us, you included.
one more thing: pain can be an enemy or a teacher, depending on how we deal with it. pain can point out to you what you have been avoiding or neglecting. it can be telling you you need to take a radically new direction in life. it can be trying to let you how wrong your thinking is in one particular area. what is your pain trying to teach you?