Thank you, everyone, for all your concern and for all the sweet messages you all sent.
I had all the symptoms of a heart attack while on a flight to Sacramento, and spent seven hours in the ER in Sacramento. They wanted to admit me for more tests, but nothing bad had showed up on any tests so far, so I talked the doc into letting me finish my trip back to DC.
I had the same scary symptoms on two of the three flights. I went straight to the ER when I got home to DC, where they kept me for a day, re-doing all the tests and still finding no evidence of a heart attack or even clogged arteries.
I was released with follow-up appointments over the next couple of weeks. Very frustrating to have scary symptoms and not know why!
The symptoms only came on while flying. This would point toward a lack of oxygen in my blood, because a pressurized cabin is only about 70-80% of the oxygen level at sea level. Beyond that, there is no explanation.
And one doctor actually said to me: "Maybe it was a panic attack. Are you scared of flying?" Um, no.
Anyway, I'm fine and I'm back. And I don't smoke!