Amrix and fms -- help muscle pain?

Sure. Fibromyalgia has muscle pain as a prominent feature. Not all of the pain is due to spasm but spasm often occurs. Amrix will help with the spasm. For the muscle pain that is not spasm, a gentle but progressive exercise program is best. Weight loss if necessary helps also.
Myofascial treatment. Amrix is for muscle spasm. A goodly part of pain generation in fm is from trigger points, tiny foci of ischemia & reactive substances (after shah at nih). Injection of these points with local anesthetic, steroids, or even dry needling is effective to abort pain generation. Kate simmons is a licensed therapist who is well versed in subject and blogs extensively about this modality at quora.Com.