H.B.
I had severe migraines for a few years toward the end of college and after I graduated. They would start with my vision looking "watery" around the edges, which would result in nauseau and I couldn't eat, stand or take any pills. I had to have my roommate drive me several times to the school health clinic for an injection of Imitrex.
I joined a study and charted when I got them (several times per month). I have since been able to control them and rarely have one (maybe once or twice per year). THese are the triggers I learned to avoid:
*Caffiene
*Being out in the sun for long periods at a time
*Birth Control pills
*Strong fragrances/perfumes
I imagine that a new medication could be a trigger as well as it changes things within your body. Just make sure to alert your doctor to any and all potential side effects so they can modify your medication if needed.
I wouldn't freak out just yet until it occurrs again. Migraines can make you feel really weird for days. I was often out of commission for 48 hours before I started to feel normal.