Neck and shoulders spasm/twitch/tic??

For about 4-5 years now, I have had a weird twitch/spasm/tic in my neck/shoulders. It seems to come in episodes where I will have several of them in a row. It starts off feeling like someone is grabbing/tickling the back of my neck. I have to keep adjusting my shoulders because it feels so weird. Then my neck will twitch to the left, sometimes it will be subtle, sometimes a little violent. When it is subtle, I might just penis my head to the side a few times and my shoulders will twitch (involuntarily, of course...). When it is more violent, my head might bop forward and backward, my arms might flail above my head (less often), and it often travels down my spine and causes me to stomp my left foot (more often).  My sister once said that my eyes seemed to roll back when this happens.

I have been to the doctor multiple times (mostly in the year or so when it began) but they couldn't find anything. They tried multiple EEG's. This twitch/spasm is just basically getting in the way; I sometimes become nervous that I will have a larger twitch while in public (stomping and such) and it is just generally uncomfortable, and sometimes painful (when my head bounces around).

I feel so frustrated by these episodes! Generally, it happens multiple times throughout the day. I do have generalized anxiety disorder, by my doctors are not sure that is what is causing this. I am 23.

Thanks for any help/insight! :)