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).
Skin disorders affecting the scalp can lead to scalp pain and sensitivity. Seborrheic dermatitis, for example, is a chronic inflammatory skin condition that commonly affects the scalp as well as the eyebrows, ears and folds alongside the nose.