Fortunately for me it isn’t accompanied by a headache. It’s just really unsettling. At least now I’ve learned to recognise them and I just try to chill out while it does its thing.
(FWIW, also a tremendous consumer of caffeine here. But this was at 17:00, a good 5 hours after my last cup.)
In addition to chugging water and staying in the dark with a face mask, I've found that taking raw honey right as it's coming on makes it go away rapidly.
My long term prevention is taking magnesium daily and LSD once or so a year. Once I started doing that the frequency went to almost zero, and whenever I don't do that they start up again.
The aura (with scintillating scotoma) starts coming on usually an hour or so after the exercise is done, and I know I've got about 15-20 minutes before the actual migraine hits. Got prescribed Sumatriptan and it maybe reduced the intensity by about 25%. I'll have to try the water chugging, maybe with rehydration salts to speed up absorption.
I have learned that while they're inconvenient, they're harmless and I just generally continue with whatever I was doing when they began. I have never been able to discern a trigger: they appear to come on completely randomly.