Welcome,
I agree with the other posters.
1) Write a letter addressed to the principal requesting that the district do a full evaluation. Changing to another district isn't going to help you at this point. The written letter is important as it sets time lines in motion.
2) Schedule an appointment with your pediatrician to talk about further evaluation and treatment options. Children with ADHD alone usually don't have this strong of a reaction to kindergarten. A pediatric neuropsychologist or developmental pediatrician would be your best bet. Some medications can actually cause behavioral problems to increase so if your pediatrician has prescribed any medications you will want to discuss.
3) Most of us have been through periods with out of control children and know it's incredibly difficult. Do get the book "The Explosive Child". You need to take the attitude right now that this isn't your child's fault and that he needs help. Back down on extra expectations--make keeping him and others around him safe.
Hang in there.