u have very sensitive scalp
u need to apply antidandruff shampoo only when u have problem
once it clear u should switch to normal shampoo.
do conditioner to keep hair smooth and soft
u need to apply antifugal lotion and mild steroid
over scalp to overcome ur problem.
what u have is irritant contact dermatitis
due to chemical in shampoo
u need to consult dermatologist