I have thick, wavy, mid-back length hair and a very itchy scalp.  I wash my hair 2-3 times a week in lukewarm-cold water and condition after.  If I have used the same shampoo for a week or more, than my scalp itches as soon as my hair begins to dry.  If I have just switched shampoos, then it doesn't itch for a day or two.  I use two different shampoos right now.  Suave (I know it's terrible but we can't afford to try out anything else if it's not going to work) and Curls Rock.  The Curls Rock was a gift from a friend but it actually seems to make the itching worse.  Any advice?  I prefer natural and inexpensive remedies as I am trying to keep my hair healthy for extreme length and we are on a tight budget.  Thanks