I just wanted to give you all a quick update (and thank you again for your advice). Because our elementary school has a new principal (the previous principal actually retired and was hired as the director of the private school where we placed DS--much to my chagrin), I called and asked to make an appointment to discuss DS and his situation/needs. The secretary remembered me and scheduled me to come in and talk to the principal 90 minutes (!) later.
I told the principal everything that happened and was happening and she told me to bring DS back and she and the staff would work with me to ensure his success. This is all ever wanted! I re enrolled him the next day, and he is THRIVING! He hasn't had any outbursts or other behavior problems. He says he loves being back at school. The teacher, who is new to the school, but not to teaching is wonderful. Everything is so much better now. He skips into the school and out of it every day. I still plan to have him evaluated, though. Just wanted to let you all know and say thank you for your suggestions. I really appreciate them all.
