Although I am not a doctor (idiots!), I believe that the master glands (pineal, addrenal, pituitary, hypothymus, thyroid) have gone out of sync causing an immune or autoimmune disorder. And I believe that FM is an immune disorder.
I am taking the following to control my FM symptoms with remarkable success:
low dose naltrexone (LDN), high doses of melatonin at night, high doses of pregnenolone 4X daily (not a steroid), vinpocetine 4X daily, and oddly enough Veinotonic II 4X daily (very important).
The low dose naltrexone (3mg) needs a prescription.
I wish other people would try this regimen to see if it works for them.
You can find information on internet on all of the above.