Heather,
I am SO sorry to hear what your son is going through... My son was bullied like crazy when he was in elementary school (5th grade) as he developed uncontrollable tics (he has a mild case of Tourette's). It was awful to watch him going through it and he too was very shy...
As much as I try to support our teachers, I am more focused on ensuring our kids have a safe environment where they can learn. EVERY child deserves that and right now it sounds like that is being taken away from your son (not to mention the [wiki2="Stress"]stress[/wiki2] of the situation could be causing him internal issues). I would go straight to the Principal. Our school had a bullying form that once filed it becomes a legal binding document that states that the bully may no longer have any contact with the child being bullied (no talking, no sitting together, no gossiping, no finger pointing, no nothing) and IF the child does there are heavy penalties.
It is a sad world we live in that parents can no longer talk to parents - but it is true. Frequently kids who bully have issues at home, therefore the parents can be equally as difficult. The school administrators are paid to handle this - the teachers are not.
Good luck - at such a young age it is difficult to teach him to advocate for himself. If he isn't already talking with the school guidance counselor and/or a child therapist - I would encourage it - it has be WONDERFUL for my son.
