I have sores and scabs on the back of my head that are taking a while to heal?

Sores and scabs: You may have either bacterial or fungus infection.You need to see your doctor or a dermatologist.

Acne keloidalis: If the "sores and scabs" are bumps arising from hair follicles, and possibly coalescing into each other, you may have something called acne keloidalis nuchae. (sounds fatal, i know, but it's more of a nuisance than anything, although it can cause hair loss.) if it's not going away, you really should see your doctor or a dermatologist for treatment.