Today, I had nothing to point to. It was 1:15, I'd been sitting and listening to lectures (one on beef, one on shchita) for three hours. I should have been fine. Instead, both the visiting lecturer AND Chef, plus two or three others in the class, took a look at me and asked if I were all right. J, who runs the school, handed me a couple of tangerines, which helped.
But that shouldn't happen.
So. I'm going to my GP tomorrow. Let's see what's going on here.