Welcome Neofate,
I am a 55 yr old man, have always been an outdoors type - hunted and fished and worked hard all my life.
I had "spells" all my life that I didn't understand - swallowing was hard at times, shortness of breath when I laid flat, would get tired face muscles when chewing etc...
Fast forward to about age 45 - I would really notice when I worked out a lot of muscle pains - figured age was a factor. Then tremors started my Doc said no worry non essential tremors - they got worse and fatigue - he sent me to a Neuro - he said no worry - Non essential tremors ??? Hmmm
Well in last 3 years a new Doc and a new Neuro said MG - tests
were positive. I have a lot of leg pain like you - knotting in the right calf bad some in left - arms etc - tremors were weakness tremors from muscle use.
Anyway I think the pain is related to pushing a muscle to do what it does not want to some days I live on vicatin - neck pain is very bad also - body starts to relax all the muscles putting pressure on your discs and joints...
Good luck - I definitely can relate!