I used to get migraines all the time when I was younger. I went through a ton of tests(EEG's were real fun, nothing like a head full of probes
) to try and figure out what was causing them and nothing was out of the ordinary. Eventually they kinda tapered off somewhat and I only get a few a year. It seems like the combinations of no sleep, stress, and lack of oxygen are my triggers(at least currently). Kinda sucks because when I'm stressed(first key) I smoke more(lack of oxygen) and can't sleep(final nail in the coffin) and always wind up with a migraine.
Your vision issues, are they the white spots? If I get that it's a sure sign one's coming SOON. The spots don't go away until the pain starts(for me anyways). Then once the spots go away, I start puking. I wouldn't wish these on anybody.
I found that massive amounts of caffeine and 1000mg of ibuprofen seem to take the bite out of mine so I can
somewhat function but it doesn't always work. I tried all kinds of prescription stuff and it all makes me sick so I have to stick with the over the counter stuff. Someone told me to try and breathe some pure oxygen when I get them(says it cures hangovers too), but I can't get any so I do the no-doze/advil trick and curl up in a dark place and pass out. Good luck, I hope you can find something that works for you. And the triggers so you can prevent them in the first place.