I know the skull tapping method you mention but unfortunately I only get very temporary relief using it - 20 or so seconds - and it's quite an unpleasant experience, if we are thinking of the same method. Mine is: hands over ears with fingers wrapping around back of head such that middle finger tips just touch, lift index finger on to middle finger, press index finger down hard onto middle finger and slide it off such that it quickly slaps the back of the head/neck (similar to a standard thumb-index finger clicking motion). Repeat this for 10-20 seconds using both hands to get about 30 taps. It's loud, not quite but almost painful, and doesn't provide very long relief for me so I don't use it much.