I had that same problem about 2 years ago, and nothing I did seem to resolve the issue until I saw a dermatologist. Be careful though, many of them only offer topical iontments that don't work. Finally I found one that injected them with liquid cortizone that shrunk them. I had to go back a few times, but within a month or so they began to shrink and my hair grew back. The dermatologist believed they were Keloids from a dirty clipper. The funny thing was, it was almost a year since I had a short cut and they just developed out of no where and they seemed to only appear on the back of my head. Trust me, they will not go away on their own and they will hinder your growth. The good new is it can be treated