It's rare, but it happens. I think that I suffered from it during the nighttime and early morning hours as I tried to sleep. Imagine all the side effects of a migraine (nausea, vomiting, upset stomach, aura, discomfort, sensitivity to light & sound) without the headache. Better than the usual thing, but, at least for me, scarier to treat with expensive drugs since I'm usually not positive that what I'm experiencing is a Migraine.
In any case, I'm not feeling so hot, but I definitely feel better compared to where I was this morning. Ugh.