[DougWebb]

What you and the people replying to you are describing sounds a lot like what happens when you try to read during a dream: you just can't. If you look at text while dreaming you recognize the words but they don't make any sense, and if you look away and then back at them they'll all be different. Looking out for this is one of the techniques for recognizing the dream state and getting into a lucid dream.

Perhaps your migraines sometimes trigger a waking dream state, or something functionally equivalent, where you're still seeing the real world instead of one your mind has created, but parts of your brain that are used to interpret your sensory input have switched to dream-mode.