Headaches can be present for many reasons, many of which are unknown. First, you can request medical examinations to exclude eye disorders, teeth disorder, sinus infection, cervical spondilosis, high blood pressure etc. as possible reasons for headache (they are very common causes). One of the most common reasons for headache is anxiety and mental fatigue.There are some less common reasons for headache like brain tumors or infections. Some types of headaches like migraine or cluster-headache have unknown reason. You can request analgesics or painkillers for temporary treatment of the symptoms, but you can also request several medical examinations to exclude the possible reasons mentioned above. You can follow up with your GP to request the diagnostic examinations.