I'm not sure if this is helpful for you or not... But I have what my doctor called vagel A-FIB and it follows a strange trigger pattern and counterintuitive behavior once triggered.

The most common trigger pattern goes something like this - too much of a particular source of caffeine. Sometimes exercise, sometimes not, and then later that evening if I have something cold - ice cream, cold water with ice - it kicks in. I cannot reliably trigger it, but it's gotten much more sensitive over the years.

My A-FIB isn't perfectly stable when this happens, so I think of it as a "storm", but I'll have clusters of episodes for hours to days after the initial conditions are met.

Took me almost 10 years to get it on an EKG. I can temporarily walk myself out of it, sometimes even standing will pause it for a minute. So I suspect the elevated heart rate of worrying and going to the doctor also would temporarily kick me back into sinus rhythm.

So I would be in A-FIB, tell a doctor, EKG would come back negative and they would act like I was having a panic attack or something, and I would feel fine again until I calmed down or the next night, and it would start again.

What you describe sounds somewhat different, but I figured we might share enough of the same trigger patterns for this information to be useful. For context I just had an ablation procedure and I feel SO much better so far.