Wow! Your symptoms come closest to mine as I have ever read. In a span of 7 years I had 3 concussions with the last leaving me without a memory of falling, knocked out for about 5 minutes, postconcussion headaches, followed by a body wide increase in muscle contractions that started after my 2nd concussion, and then essential myoclonus. This has been going on since 1999. I take klonopin for the myoclonus. My muscles are tight but when I have an episode, generally started by someone touching or injecting around my right shoulder area, contortion is a good word for a description of the visual. Just had a bout at pain management that lasted over an hour. Time is all that helps resolve it as I am allergic to so many meds. I have been told they are all in my head and I am anxious. I deny either, well I 'm pretty sure the head injuries are responsible but that's not what they mean when they say all in my head. I find both myoclonus and sustained contractures exhausting and moderately painful compared to my other pain issues.