I get migraines from time to time. Sometimes I go months without one, then sometimes I'll get 3 a week. I get aura, nausea, confused, and my left side goes numb.
I've learned what works best for me, but everyone's different. I'm most likely to get one if I have low blood sugar (miss a meal), am stressed, not sleeping well, and/or have been drinking caffeine. Also, if I don't exercise for a few weeks, it's more likely.
I can usually avoid the headache part if I immediately eat a snack, go to a quiet dark room, and take a nap. A noise maker helps me to fall asleep and keeps me from thinking; You have to turn off your brain as much as possible.
I've gotten them while riding and it's pretty dangerous. I can't see where I'm going and I get confused easily. I head straight for home or call.