Could be a lot of things.... Whereabouts in your back is the pain? If its quite general I would suggest a joint supplement like devils claw or glucosamine. Be careful though make sure you get the right strength for your condition.

I buy my multivitamins from a company called simplysupplements, and I think they do joint care stuff too

http://www.Simplysupplements.Co.Uk

I used to suffer from back pain and I didn't want to use drugs long term. So I took these natural supplements that I market and the pain gradually eased and now i've been pain free for two years. Perhaps they will work for you too. If you want to find out more about the products what I used to get rid of the pain, you can send me a private message. I don't want to breach the forum rules by posting more details here.

Dietcoach