i no you said that your tried tea tree, but have you tried mixing tea tree with argan oil? or jojoba? if that really doesnt work, there are herbs that you can get that can help with scalp problems: marshmallow root is wonderful, to make it better make a rinse combining stinging nettle as well, ive read that stinging nettle is great for scalp conditions. use that and marshmallow root as a final rinse and see how you go