Dry flaky scalp (not dandruff)?

[Jessica Edmed]

I have been suffering from a really dry scalp for a good six months now. I'm twenty and have tried loads of different shampoos including T gel and head and shoulders (I went through a couple of bottles for each one) neither have helped. The dry skin is located right on my hair line and goes back about a centimetre. At the moment it doesn't itch but I think that is because I'm trying a different shampoo from Aveda which is designed for dry scalps, I have the shampoo, conditioner and a spray treatment thing. The combination of these three has really taken away the itch but the itch was in a different place to the dry skin. The itch was located across the crown of my head and although I couldn't see was described by a friend as really red and angry looking but it isn't like that at the moment. I know I don't have dandruff because the flakes are way too small. I know I'm really stressed at the moment because I have finals coming up but I've never suffered from this when I've been really stressed before.
I'm just not sure what is causing these problems and how I can get rid of them.