Ok....I gotta respond to this one.
Fibromyalgia is no laughing matter disease in and of itself. It actually affects MORE parts of your body than MS. The awful part about MS, though, is that it is (or can be) disabling, whereas fibro is not. BUT fibro mimics MS almost to a "t" with some additional symptoms on top. Some people even get so spastic and deal with other unrelenting symptoms as to require assistive devices such as canes and wheelchairs, etc.
It certainly is NOT any less difficult to deal with symptomatically.
Here's a good website about Fibro: http://www.fmpartnership.org/engmonog.htm
Fibro seems to be due to a dysfunction in the HPA axis, (which isn't any laughing matter), i.e. the hypothalamic-pituitary-adrenal axis, and also the sympathetic nervous system, AND the autonomic nervous system, in ADDITION to the central nervous system. It affects just about everywhere.
And Fibro is also very difficult to treat and keep under control.
So, don't feel as if your doctor is trying to diagnose you with some disease that is "all in your head" or something. THAT is an old wives' tale. Remember, they used to say the very same thing about MS as they did Fibro.
Now they have found they were wrong about BOTH diseases!
Besides, most of the symptomatic treatments for both MS and Fibro are the same.
Hang in there! Fibro is no fun.
EDIT: Bottom line being.......Fibromyalgia IS a specific disease and a specific diagnosis.
SECOND EDIT: Oh, and Fibro is not known to be associated directly with inflammation. (Sorry, one of the responses you received seemed to be implying that they were telling you it was "all in your head", and it isn't. They used to tell MSers the same thing, and I hate hearing that in response to anyone's medical condition. Again, fibro is not a fun disease nor is it an "all in your head" disease.)