At this writing, the debate continues about whether FMS is progressive. Although not contagious or hereditary, studies are revealing an inherited tendency towards FMS within families. Although considered a permanent condition, remissions can occur. Among the abnormalities so-far found in the brains of many patients with FMS and CFS are reduced blood flow and energy production in key sites of the brain. While any such changes might themselves merely be symptoms of the syndrome it is thought by many researchers that the most important imbalance in these conditions probably lies in the brain and central nervous system itself.
Physical therapy is very helpful, but heavy resistive exercise, like weight lifting, is too painful.
But gentle aerobic exercise, like low-level treadmill walking, biking or aquatics are particularly helpful, it also improves cardiovascular fitness which is always important. A stretching program can help those muscles become more flexible and reduce pain. If anxiety and depression are severe, psychological counseling can help. Clinical trials of these kind of drugs haven't been very convincing. I would talk to a physician before starting any of these treatments.