One of the main causes of sinus drainage is simply being alive. Every day the human body produces several liters of sinus fluid and mucus, and all of that natural liquid must go somewhere.
It is a area of tenderness of the scalp in which people also sometimes feel stabbing headaches. Others just feel very sore and tender to the touch. It is felt to be caused by irritation of the connective tissue which attaches the muscles of the scalp to the skull (cranium).
Excessive dandruff can signal a dry scalp. Braided hairstyles can pull at the scalp causing dryness and irritation. An allergic reaction to a new kind of shampoo could cause a tender scalp. Diet may affect the health of a person's scalp. Dry skin may contribute to a sore scalp.