Headache is one of the most common disorder of the nervous system. It happen when the nerve endings in different parts of your head and neck become irritated. Common complaint are pain or discomfort in the head, scalp, or neck. A typical headache may lasts for about 3-4 hours. But for some people, severe headaches drag on much longer, sometimes for several days or months. Here are some of the possible causes of your "never ending headache" namely: Hemicrania Continua - It is