What Causes Severe Pain On Scalp At The Crown Of Head?

The scalp at the crown of my head (top center) is very painful to touch - a small section the size of my finger tip. the hairs that grow there are very brittle and break easily. I get some relief by pulling the hair out but the section still hurts. Dermatologists have biopsied the area and found no skin condition. Please let me know if this is a nerve problem...this has bothered me for 20 years.