I'm afraid I don't have a lot to offer with regard to this other than to say I developed what I presume to be RLS quite a few years ago now. (I never saw a physician about it.) Over time, it seemed to spread throughout my body. So now I have that RLS sort-of feeling pretty-much throughout my body. I once mentioned it to the pdoc I used to see. He offered to write me a prescription for Klonopin. He said it would smooth out that RLS feeling. However I declined.

I sometimes feel the need to "jerk" one of my legs when it feels as though that RLS feeling has built up to an uncomfortable level in it. But it doesn't happen involuntarily. I do it intentionally. I was on the maximum recommended dosage of Cymbalta for a while a few years ago. And I developed something in my arms akin to what you describe. Where I would notice it, in particular, was using my computer mouse. I'd be moving it around on the mouse pad & all of a sudden my arm would jerk forward slightly. Once I was off of the Cymbalta this jerkiness went away.