FM can be a very debilitating, painful and difficult illness to have but it is not life-threatening. FM is often triggered by some accident or illness and the pain it causes tends to spread at least at first but there are no real stages to it.
The stage part really comes with the patient and they learn more and more how to cope with it. FM best responds to an multi-dimensional approach often incorporating drugs for pain or sleep, good nutrition, good sleep hygiene, the right kinds of exercise, employing stress reduction practices, etc.
One key is working on parts of FM that have the potential to effect other aspects of the disease. Because poor sleep, for instance, increases pain sensitivity which in turn makes it more difficult to sleep, its important to figure out a way to get a good nights sleep that leaves you feeling rested in the morning.
For more on the multi-dimensional approach to FM check out Health Centrals FM section.
http://www.healthcentral.com/chronic-pain/fibromyalgia.html
Good luck!