My jaw and face have trembled from the beginning with this stuff. I am 6 months into BFS right now. The jaw shaking, tongue shaking, and face trembling when I make a half smile, etc. does worry me. I worry that the shaking is coming from weak muscles straining to hold a certain position/expression. When I put my teeth together I can feel them shaking and scratching against each other as my jaw muscles tremble....it worries me as well, but I hope it's just part of this whole bfs thing. My most obvious symptom though is still the 24/7 100+ a minute twitches in my calves and feet.....