Frozen peas. Enough said... actually no it's not and I shall explain. I deal with them frequently. Have had all my life. The earliest I can remember having one that made me cry myself to sleep was when I was about 5. I found the most effective way to dial them down is to use either a gel style ice pack or bag of frozen peas on the top of the head, or back of the neck. Anything that is frozen but can be broken up to conform to your neck and head.
My deal has never been identified. I've had it all done too that a hospital can throw at me. MRIs, ultrasound, you name it they tried it. The best answer they gave me was it must just be the body's way of releasing stress.
My studies of my circumstances showed drastic changes in atmospheric pressure, particularly the transition times between winter and spring, or summer into fall, always make me suffer immensely every year. I also have allergies to dust and sometimes being stuffed heavily will do it. One other thing which I have been eliminating from my diet and has been showing good results is gluten. I'm not sure if you have a craft beer down there called Barking Squirrel, but it's here and it's horrible. Not only for taste but the concentration of hops in it will trigger the most severe of migraines on me in less than half a beer.
Other factors that I have found are these damn LED lights everywhere. The city uses them, headlights in almost every newer vehicle and replacement LED conversion bulb for older vehicles. It's that useless snow white glob of lumen grade light. I use an LED light in my bedroom but it's a 2700K series, very yellow like natural sunlight or the old incandescent bulbs and rarely do I get an LED triggered migraine. Those cool white ones and florescent tube lights...major triggers.
When I get one at work, if I can't get to my prescription soon enough I go for a sink and as cold of water as I can run all across the back of my head to freeze me. It's the most instantly effective counter to the pain. If I don't do that, I'll start to sweat bullets and inevitably puke my guts up. Cold temps, kills migraines. I feel for ya my friend, it's a pain I never wish for onto anyone...or any other pain but you know what I mean
...and yes I do lose my vision too as a precursor to the most serious pain about to strike. I get a form of radiant heat waves-like illusion taking away my peripheral vision, then like clockwork at about the 20 minutes to follow mark the serious pain sets in and I'm toast for at least 24 hours. Longest strong headache I've ever had lasted 31 days straight with no let up. Ice that melon on your shoulders, it'll do a world of good for you.
