What are these scabs from on my scalp and upper back?

[Letah2]

i have about 3 hard scabs in my scalp for 3months now on and off since last Spring. I then developed sores on my upper back. My PCP said she didnt see anything in my scalp but referred me to a dermatologist. The Derm Dr told me she saw nothing also. She told me to use thick balm like Ceravae on my back and head everyday after bathing. Ive been using Avene (no parabens) It seemed to be ok during the summer.  I've tried everything from Nix, vinegar, steroid ointment. washed with Hibiclens and used Permethrin cream!  They seem very deep in the skin and leave a scar like hole when I did pick off. They don't itch but feel tigh. They are  annoying and hurt when caught in my comb. My PCP suggested a referral to an infectious disease doctor. I wonder if anyone has a clue what I have before I see another specialist? Thank you.