P.M.
This is definitely something to talk to his doc about, and until you have insurance, no huge changes are too likely to occur. You could make an appointment now for next week, though. And if possible, take a video clip with you, and perhaps a diary of how many times a day you see it. Mysterious symptoms have a sneaky habit of disappearing at the doctor's office.
This could be so many things. A kink in his arm muscle, or in a joint. Neurons firing in the brain. Early signs of Tourette Syndrome. Let us know what you learn. I wish you the best.