yikes, how awful! hope you're starting to feel better?

I think heat may have played a role in your migraine trigger. I sometimes get migraines from being too hot when I'm doing an activity, and one of the worst migraines i got was when I stupidly went hiking by myself with insufficient water. That was both heat and dehydration, and I was lucky to have made it out in one piece considering I couldn't see straight and was shaking and nauseous.

I agree with smilingcat in getting a medic alert bracelet just in case you do get in a situation when you can't communicate properly.