I have had a little luck explaining that it's not really about headaches (you CAN get atypical migraines that manifest only as the aura and the rest of the weird symptoms - doesn't happen often, but I found that out when my friend got diagnosed after being terrified about brain cancer for a while due to neurological symptoms), it's a neurological condition which has headaches as one of its symptoms, and the headaches can be epically and overwhelmingly bad but come with all the rest of this stuff TOO.

And then assuring them they can have the worst headaches ever without, in fact, having migraines.

MMV, of course.