Hm. Well, clearly I ate something that should never be eaten, or touched something that should never be touched, or perhaps just was nearby something that one should never be nearby. Quite the odd day or so. Not an illness, just a pervasive feeling of toxicity, mild fever, an entirely conceptual mild nausea, etc. But very intense. I'm not generally susceptible to those sorts of things, and I have had the good fortune in my adult years of very rarely being ill.
Perhaps with the chill in the evening, the microbiota of the old city were able to make inroads. Or something was off in the kefir at the supermarket cafe.
The closest correlative would be the second half of the first bar exam that I took (and passed with flying colors). On the Upper West Side, a large armory gymnasium. At the lunch break, I think I had the sweet and sour tofu from a cheap Chinese place nearby. And I assumed that it caused the mind-bending unease that I felt in the second half of the exam, but in retrospect, I don't think that was it.
There was also a very peculiar episode in the second year of the JD that had something to do with environmental toxins, but I've not talked about that, for a few different reasons.
But this was much the same, in that the unease, aside from the mild fever, was entirely conceptual -- to put it bluntly, there was no chance of my revisiting my lunch. (I can't recall the last time that that happened, tbh.) But very intense, and some lingering feelings of toxicity. Will hydrate, rest, and try to get back to the morning exercise, but certainly not for the next few days.
Once I was ambulatory again in the (late) morning, I washed out all the clothes recently worn, swept all the floors and wiped the surfaces. Seemed wise.