There are some hidden causes that can cause headaches. Vertebral subluxations can be a cause you have not considered. Neck tension caused by poor posture can cause vertebral subluxations. Because of that medication will not always be able to help headaches. Getting rid of stress and tension will help you long term get rid of this pain. Staring at a computer screen for hours can cause eye strain also leading to headaches. Dehydration and emotions can also cause headaches.