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).
This skin condition can make your scalp itchy and flaky. It's most common in babies and children, but anyone can get it. The cause is unknown. Moisturizers and prescription steroid creams can help relieve the symptoms, as can avoiding harsh soaps and scratching. It also helps to avoid stress whenever possible.