According to spine-health.com (http://www.spine-health.com/treatment/pain-medication/ultram-pain-reliever) ultram or tramadol is frequently used for chronic back pain. Ultram is technically a narcotic but it is a different kind of narcotic which has a very low incidence of addiction or the problem of increasing tolerance to the drug. It's also not as strong as Vicodin.
For more information on ultram (http://www.healthcentral.com/chronic-pain/find-drug-25432-25.html)
Good luck with your back pain.