What Causes Soft White Scabs On My Scalp? How To Treat Them?

I have a few soft white scabs on my scalp. When I pick them, they are not crusty like a regular scab, but soft. They also bleed sometimes when I pick at them too much. They started about 6 months ago. What caused them and how do I get them to stop. It started with 1, then gradually increased to 4 or 5 now.