All I can tell is what Gary Craig says about pain, there is usually an emotion behind it. Tap for the emotion if you are not sure what it is ie "Even though I don't know what emotion is behind this pain I..". Things that cause stress in the course of the day can give us back/neck/shoulder/headache pain etc. Sometimes you have to be a real detective to figure it out but once you can trace the pain to an emotion EFT seems to work much better/faster/more permanently.