Raised black spots on scalp

[Teebeedee]

I've had several black spots on my scalp for the past 6-7 years. I've seen several dermatologists but none of the treatments have worked. All of this began with severe flaking on my scalp. Large chunks of scabs/flakes that I could see where my hair grew from. Then I got one large area (the size of a pencil eraser) that scabbed up but transformed into a persistent raised bump. The bump flakes but it never goes away, and now I have about 6 all in the back of my scalp near the nape of my neck. I'm an African American female and the bumps are black. Please help!