hello and welcome to health care magic, I am Dr Sriram nathan and i Shall try to help you out with your problem. You seem to have injured your drum or canal when you got slapped. Although your GP does not think so, you definitely need to get the drum examined by an ENT with an instrument called the otoscope for correct diagnosis. Many people do not realize the danger of a slap under closed high pressure environment of nose and throat and ear In a closed environment of the ear canal and drum a slap causes such intense pressure that the drum ruptures and causes pain and hearing loss which you are feeling right now. But do not worry and do these: -take a course of antibiotic like amox-clav and anti histamine like levocetrizine in consultation with your doctor -get an audiometric testing done -Do not take head bath for two weeks and after that do not allow any water to enter the ear -Do not put any other ear drops -If the pain is more then you may consider taking injectable medications for better and faster symptom control. Remember that if you keep your ears clean and dry the drum will recover In any case you can get your drums examined by an ENT with otoscope and get back to me with the report. You must remember that eustachian tube dysfunction will usually not present like this after a slap. If any other doubts get back to me regards Dr Sriram Nathan