(Sahloknir - not a happy chap)
Otherwise known as "why Hannah shouldn't read medical articles first thing in the morning".
Having a quick skim read of this:
"A Workout Without Working (Much)"
I came across the word "sarcolemma" - the membrane around the muscle fibres.
My not-fully-awake-and-a-bit-foggy brain read this as "Sahloknir", which followers of Skyrim may recognise as the somewhat angry dragon you encounter just outside Kynesgrove in The Blade in the Dark quest.
So, quite by accident I may have solved the mystery of Fibromyalgia.
We're just full of angry dragons.