First, I am sorry for your situation, which, as you have likely read, is quite common on these threads. :-(
The Davidson Website has many good articles that you could go through to see what might help inform your path. I personally would not jump to homeschooling unless you are really excited about it, at least not before trying a few more times with the current school. You can reasonably assume, but of course verify, that your son's teacher has zero or little experience in knowing what to do with a gifted child in K. That means, unfortunately, you get to train the trainer, so to speak. Sometimes this works, sometimes it doesn't.
Did you happen to mention to the teacher the change in attitude you are seeing in your son? Most teachers do care about how children feel about school.
I would definitely ask for end of year K and 1 tests to be administered. Be sure your son knows the intent is to try to figure out what he knows, so he should do his best. Once that's done, you may need to schedule a discussion with the principal and the teacher. Does either know that he had previously tested at a 99% into a self-contained gifted program?
