There may be some doubt about what's just "a bad headache" and what's a migraine, but those who suffer the latter are absolutely sure what they're feeling. Often, their initial clue is the dreaded "prodrome," a sense that the migraine is about to occur. Then begin the throbbing, pulsing pain and extreme sensitivity to light and sound, maybe with nausea and changes in vision, such as the appearance of auras. (BioWorld Financial Watch)