One of the things John Lowe spent his life doing was to track down evidence that clinically, fibromyalgia and hypothyroidism are the same thing. He certainly thought he'd proved it, and wrote a review paper called

Inadequate Thyroid Hormone Regulation as the Main Mechanism of Fibromyalgia: A Review of the Evidence

You can find it here: http://tpauk.com/main/dr-john-lowe-overview-of-important-articles/

I haven't followed up the references, but he gave four for exercise intolerance/fibromyalgia and four for exercise intolerance/hypothyroidism.