I have the same thing. I used to have a scaling dry scalp and then a few years ago, it changed to scabs. The scaling stuff went away. I think mine is related to the autoimmune/hypothyroid problem that I have. (Hashimoto's Disease) It is known to affect the skin of people that have [it in lots of different ways,..but not a given).
I once saw a person with autoimmune disease on here asking if others [w/ AI disease] had such a thing. There were quite a few that did. Do a search on this board for scalp/scabs/autoimmune. Not to say that you have AI, but it does seem related for some of us. I haven't really tried that hard [yet] to work on mine. [haven't seen a Dr. yet...mine [I would say] is moderately bad. I hate it... but I feel so well compared to a couple of years ago, that it's hard to get upset over this.
I will eventually see a dermo Dr. and work on getting this thing under control. My hair looks fine tho. I just need to QUIT picking them off!

My husband gets so mad at me! (I told him if they were on his scalp, he's be picking them too)
Good luck!
Deda