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).
Scalp sensitivity has several origins. It could be caused by an imbalance in the sebum secretion process, which leads to irritation. Pollution and stress can also irritate the scalp. In fact, pollution coats the hair in harmful elements that create a dull film over the hair and, like stress, generate free radicals.