Are these short twitches or jerks at the full range of motion of your head and neck ? I have had head twitches but they have never been more than a few inches. Involuntary jerks do not involve enough muscles to cause the forces required for a concussion or what would be considered violent shaking.

Shaking your head violently would be like what happens when someone is head banging to music. Head banging usually involves not just jerking the head but also the shoulders and upper body.

If I remember correctly, you have asked these questions before and I answered. Has something changed ?