Did your physician check you for scoliosis? This can cause severe back pain as well.
http://www.mayoclinic.com/health/scoliosis/DS00194
What type of doctor did you see? Do you have other symptoms of FMs outside of the back pain?
Do you have any treatment plan? Medications? A diagnosis alone is hardly helpful. How is your sleep? This is always the first place to start with Fibro patients. Unless you're getting a good nights restorative sleep, nothing else you do matters. Do you take anything to help you sleep? What about stretches, not exercise? Physical therapy? It seems to me that if you have significant pain and no relief, it's time to visit the doctor.