Need a cure for sever dandriff and thining hair?

In the last few month my hair and scalp have been a serious issue I have tried all sorts of shampoos... now I have graduation i a week ad I really need something to make this go away.... my scalp is not bleeding or have sores on it just lots of dry skin flakes and such but also my hair has been thining out and that has made me very self counsious... please help thanks