I was diagnosed with fibromylagia before being diagnosed with Hashimoto's. Several years of severe pain not helped by painkillers, muscle relaxants, massage and even yoga.
All my fibro symptoms did NOT go away until I was on an adequate amount of natural dessicated thyroid (first old Armour, now Erfa).
Generic levothyroxine (250 worth) helped some; the addition of Cynomel/Cytomel in a combo of 137.5 levo and 37.5 T3 helped more.
But up to six grains Armour cleared all fibro symptoms. I am now on 5 grains of Erfa and all is well.