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).
It is subject to multiple aggressive elements on a daily basis, which cause it to weaken. When confronted with certain factors, such as pollution or stress, the scalp develops an acute level of sensitivity. In addition to itchiness, there is a sensation of dryness and the scalp feels painful to the touch.