Last time I got the theory that I was over heating, because when I had to quit I felt immediately better when I put a wet towel on the back of my neck.
So I went and found a special cloth my mother bought me for hot taiko days which contains the chemical that holds on to water. The idea is that you soak it, and then tie it around your neck to feel cooler.
AND IT WORKED!
I did the whole class and didn't feel remotely nauseous!
She said, "well maybe you are just stronger." I said, "no, it was like a switch!"
So apparently my body has a heat dump problem and I seem to have foudn a workaround.
I wonder if this is why exercise so often makes me feel just horrible.
(BTW, except for the classes where I did feel queasy, TKD makes me feel pretty good. Every now and then I'll twig my knee or shoulder, but other than that it is really making me feel better physically. Mentally I'm in a good state where I've stopped caring about how fast I progress, which for me is important. I'm enjoying the doing, not the goal.)