Fibromyalgia can often be a catch all diagnosis when medical doctors don't know whats going on. You will not have lasting success if you are just trying to suppress symptoms.
Fibromylagia often is a condition of excess internal toxicity which causes decreased energy production in the muscle cells. So looking at supporting mitochondrial function is a must.
You would be better served to try to find a licensed Naturopathic Doctor to help you detox before building up your energy reserves then trying to go on a suppressive medication.