@shoshin thanks for the reference to Roemheld syndrome!
https://en.wikipedia.org/wiki/Roemheld_syndrome
I figured out some of the same treatments, myself, including Gas-X/simethicone, Pepcid, Tums and Klonopin (similar to Lorazepam).

I have several spinal fractures and can experience a feeling of fullness and a feeling that my diaphragm has moved up, before an afib episode. Lifting and reaching will do that, even the tai chi I have always loved. I believe it is related to there being less room for everything and so there is pressure on my heart, but it could also be on the vagus nerve.