Hello,
It can be due to small wounds inflicted by head lice. Other possibility is of a fungal infection( less likely). Wash the Clothing, bedding, and towels in hot water and dry them in sun after machine drying them. Topical permethrin or Lindane cream may be needed for lice which are available by prescription only.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.