I would suggest for the time being to swallow what you are feeling and be a detective, polite, but firm, detective
Go gently ask the teacher(s) what has been happening. Show your concern for your son and for the teacher, like "hope he hasn't been a lot of trouble..." -- what is the problem? how can you help? etc etc etc
Make mental notes, take some notes.
AFter meeting with teacher(s) write/type down everything.
Also, if you can, meet with principal. Bring a friend or spouse if you can. Again, no matter how "emotional" or "strange" the other person gets, keep your composure. You're the detective first to figure out what is going on first. Don't take no for an answer. You deserve to get a meeting.
After all meetings/chats/phone calls/ -- always take down all the notes.
Because if they don't give you the facts in writing, you want to hear it from them, and you put it into writing ... if it is beneficial to you.
Just some ideas. It may or may not work in your situation. Hope some others come to offer advice. Best of luck. Let us know how it goes...
