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).
Magnesium chloride, the kind of magnesium that is found in magnesium oil, is used to nourish tissues, including the scalp. The problem with magnesium sulfate is that it can form crystals in the hair.