My son & his kindergarten teacher?

Have you tried to bring this up at the school? Make an appointment with the principal and the teacher. Tell them your concerns, and be honest. It is horrible that your son is going through this. You don't want this to ruin your son and his outlook on school, after all, he needs to go to school for the next 12 + years. If you can, see if you can actually sit in the cl, to observe and ist your son if needed. If things don't get better for him, then yes, put him in another school.