I seem to have just joined an elite club.
About an hour ago I started having trouble reading my computer screen. Things in the very center of my vision were blurry. After a couple of minutes, the blurriness resolved into a crescent-shaped shimmery patch just left of center. This gradually expanded and moved leftwards and out of my field of vision. Everything is still slightly sharp-edged with slight chromatic abberations.
A few minutes after that I began to get a throbbing headache in my right temple. It’s not quite debilitating yet, but I’m beginning to feel nauseus.
I understand that these are the symptoms of a classical migraine. Joy.