hey Mark,
I get this too! My body jerks and the worst areas are also my legs. It happens with my chest (I was having severe chest pain to the point I was sobbing and I got giant spasms that jerked my chest every which way the night before last!), my eyes (bad twitches!!

), and sometimes it also happens with my arms. My rheumatologist said I have bad tremors on the left, but I also deal with it on the right when walking... I can't walk unassisted because the tremors are so bad... but when I am staying still trying to relax it happens when I am not even trying to move.
ENOUGH to make you feel NUTS!!
I hope you are getting through the day with the nasty mouth/ throat allodynia and burning! I know how it is...