what i have learned from lurking on google.com is .. Anxiety disorders can produce variety of symptoms that could mimic (or provoke):
1. hypertension
2. stroke
3. cardiac diseases
4. migraine
5. ALS
6. other various neuro disease
7. tooth ache
and many more..
(but that doesn't mean that you should sit back and relax assuming that it's all anxiety.. please get all the possible tests done to rule out ALS)
All I can tell you is that there is no pain associated with ALS. The muscles twitch, but the shaking does not sound like ALS, either. Good luck to you!