LouH
Sorry to hear you are having troubles coping with the mouth movements. I dont know if you have parkinsons so perhaps your involuntary movements are different to mine. All I can say is that mine started about couple years ago, thats 4 years after diagnosis of parkinsons, and its definitely worse when I'm anxious (like had a row with the wife or heard that our grandson was feeling unwell). The chewing gum answer is not foolproof but I think what it does is to give my face and jaw something to do and, with any luck, the sharp end of the anxiety has by then gone. Why dont you just try something similar, if you can't chew gum, try sucking a sweet....you know give your mouth something to do. Also, just try to work out what triggers it to see if you can gain some sort of control. I'm afraid the above is not a very clinical solution but I'm just trying to tell you what helps me out sometimes.
Hope you find the answer and keep in touch
All the best BILLY