Personally, I suspect my TOS is a result of collagen degradation that may accompany ME - fwiw, I don't have the neuropathic (painful) version of TOS.
Yes, I still get PEM if I exert too much, especially my arms.
My GP is at St Michael's hospital in Toronto, so I saw somebody at St Mike's, sorry I don't recall his name, but it was something middle Eastern (like Al Kabar) -- I do remember asking him if TOS had anything to do with ME, and of course I got a blank stare, he didn't know what ME was and showed no interest.
I have a very low all around opinion of St Mike's so they are not a recommendation.