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).
2 doctors agreed: Could be occipital: Occipital neuralgia is a condition that may cause tenderness on the back of the scalp. It is a little different than a tension headache- the source and treatment are different for example. An injury or problem with the neck is a second possible cause.