I get migraines with auras. lately, i'll get an aura and it will go away after about 20 mins. then a hour later it will come back. why is this?

A migrainous event: can be divided into five separate phases: the prodrome, the aura, the headache itself, the termination of the headache, and the postdrome. The termination of the headache occurs gradually. It may last for hours or more than a day. Although a patient may feel better, some symptoms may persist. As the intensity of the headache wanes, the headache phase blends into the postdrome.

Migraine headaches: You don't list prophylactic or abortive therapies for migraine headaches. See a neurologist for a full evaluation, diagnosis, and treatment recommendations. In the meantime, identify your headache triggers and keep a headache log (timing, frequency, duration, location, characteristics) and take it to the neurologist. http://www.nlm.nih.gov/medlineplus/migraine.html