This could be a scalp fungal infection.

There is a special OTC shampoo called Nizoral. Selsun also makes products that work. Give those a try.
People on high dose prednisone can get skin fungal attacks.
This is due to the reduced immune response in the skin and also the elevated blood sugar the pred causes. If you perspire alot, this also feeding skin fungal organisms.

There is also a liquid anti-inflammatory liquid called Scalpicin.
It works pretty well. The doctor can write an RX for stronger types, but the OTC one can work well and is less expensive.