my stuttering is going to cause me to break my neck

my stuttering is going to cause me to break my neck For years now, my blocks have gotten significantly worse. Recently, the worst its ever been. One thing I do, that I have never seen anyone else do, is when I go into a block my head sort of starts banging. Yes, like head banging to music lol. I tense up real tight and start almost convulsing...I cant seem to stop once it starts. I have been tested for tourettes and stuff like that, because it was recommended by a doctor, which all came back negative. Sometimes I will tense up and just hold my head down really tight so my chin is jamming into my chest. The whole thing is really starting to hurt my neck, to the point of it aching almost every day when I wake up. Does anyone else do anything remotely similar to this? I have had a couple people in the past get extremely worried that I was having a seizure or something similar when it occurs.