I'm not too sure, you feeling faint etc, got anything to do with other issues coming to surface, past trauma so on. I feel the same way, not only at tapping, but when repeating positive affirmation for example, or when i am doing "psychic spells". I know it sounds crazy, but always need to stop, I feel nauseatic, tired, dizzy all of a sudden. Sometimes I come to the conclusion, that may be, these self-help courses are too powerful for people like you and me. I don't have the answer, but I know how you feel.