Abdominal pain can have many sources since many of our organs are located in that area. However, since I don’t have more specific information about the nature of the pain you describe as behind your belly button - like how often it occurs, what type of pain it is (sharp or dull), or if you are able to relate the abdominal pain to certain activities or food, I recommend making an appointment with your family doctor. He or she can help you pinpoint the pain, and if they are not able to make a diagnosis at that time, they might order additional tests or refer you to a specialist.