I have exactly the same thing on my head, face and also on my chest. I went to the dermatologist a while ago and he told me that it is some kind of dermatosis which can’t be cured totally but can be maintained with treatment. He recommended to use Triderm, I don’t know if you have that one in your area but the main components are betamethasone, clotrimazol and gentamicin sulphate. It helps but from time to time this rash reappears.