The post above describes what happened to me long ago. In my case I was 21 and my first day on the job. I drank a Diet Coke and it went down funny and I felt a burning in my chest. Next minute (as it felt to me) I was struggling to get up off the floor and the paramedics were there. Apparently I passed out, fell out of a tall drafting chair, turned blue and purple and “had a seizure.” They wanted to take me in, but I refused because of cost even back then.
I did go for all kinds of tests on my own. EEG, EKG, heart monitor, etc. nada. They called it a vasovagral response and not to drink Diet Coke in the morning. I have long since disregarded that advice but for many many years I wouldn’t drink anything while driving. Never happened again.
but I was only 21 and very healthy. I would probably touch base with a pcp if you have one.
Edit - I should also add I have low pressure and resting heart rate naturally, so any drop is probably what caused me to pass out (90-100/50-60 and a heart rate in the upper 40s/low 50s)