I have suffered from itchy dry scalp and breakage for years (until I saw a dermatologist). I (and my mom, sister, etc.) have seborrheic dermatitis. The worst that it ever got was very itchy scalp and breakage to the root on the top of my head, then the nape of the neck, then the sides. Stress made the problem "spread". Any-who, I eventually went to the dermatologist and he prescribed an ointment for my scalp that I needed to use overnight. Then I had to shampoo with Neutragana T-Gel Shampoo at least twice a week. FYI - when I lived in a really cold climate the dermatitis even spread to my face only in one area.
Now that I live in a warmer climate, it does not really bother me. Definitely no breakage. The dermatitis is concentrated at the top of my head. What I do now is apply avocado oil to that area (I found out that this oil helps with skin conditions including derm.). Also, if the itchy is bothering me, even a little bit, I apply Neutr. T-Sal shampoo to that area only (this shampoo is very drying to the hair) follow the directions and leave on for several minutes, then rinse and repeat. Then I proceed with co-washing my whole head...If you are not able to get to a doctor, this may help you. Before finding the avocado oil, I never applied any oil to my head, because it only clogged my pores and made the itchy worse.