I have had 2 migraines - one being of the ocular variety as you described above. I was sitting with a client editing music on Pro Tools and all of a sudden my vision appeared to be looking through a drop of water in my left eye. The portion of my vision being effected grew for about 10 minutes or so and then it seemed to 'thin out' and go away. I never really got a headache with that one but went to a doctor as I was really concerned about what had happened, and he said that in some cases a migraine can occur with no pain. The second time I got one it was after a fall and I had hit my head - I instantly got that same vision anomaly and a screaming headache - to the point that I was nauseous, and no it wasn't that I had concussed myself as it wasn't that hard of a blow to my head.
In a few instances I have had a headache that was accompanied by that dizzy, which way is up feeling and a bit of nausea, but they never led to full on migraine.
I have this weird thing called Miniers Disease, which is a really bizarre inner ear condition that can cause vertigo to appear at random and in a flash. I have really only had that happen once, but I usually have a somewhat ambiguous sense of which way is truly up. This is eased by watching caffeine, sodium, and alcohol intakes.