A.T.
You definitely have my sympathy...One of my twins (age six) went through a terrible time in Kindergarten last year and did develop a nervous tic with his eye (just the right) whenever he had to be around his "great" teacher...It wasn't such a great situation for him. I had a terrible time asking the teacher to spend a bit of extra time making him feel more comfortable and was told it was HIS problem and not hers.
My solution was to pull both of my sons from first grade in the district this year and give them some time with me. It's a lot of work but amazingly my six year old does not have a nervous tic - and they are both loving the attention. They WILL have to go to school next year - but as a parent I feel they both need to realize that learning is fun - not something to be afraid of when they are so young.
I am not even sure if homeschooling is an option for you - but there are also online activities that may make him feel a bit more comfortable with the material in class if that is what is making him anxious. The social aspect can be tackled with extracurricular activities (I have my two in gymnastics classes, also).
Hope this helps a bit -
A.