I think it sounds like you have classic dry scalp. This means the skin on your scalp is flaking because it is DRY! That's why the tea tree oil (which is very strong and drying) is probably removing more moisture from your scalp, resulting in more flakes.
It's good to exfoliate and cleanse every once in awhile for the flakes, but too much can just exacerbate them. Something that really works for me is rubbing coconut oil all over my scalp, sleeping in a shower cap or plastic wrap, and then washing it out in the morning. My scalp will be completely itch free after that. I also like to mix brown sugar in with my conditioner wash to exfoliate, but no more than once a week. That really helps get rid of the flakes.
Hope that helps! I have always had dry scalp too. It's annoying :P