You don't have any feeling of tightness in your throat, do you?

Dystonia is a movement disorder with involuntary muscle contraction. Dystonia usually disappears during sleep. The problem is confined to the brain, and doesn't fall under the neuromuscular specialty. Neurologists who are Movement Disorder Specialists treat things like Parkinson's, Essential Tremor, Dystonia.

If your other doctors can't find any cause, maybe this is something to consider?

Tatia