Physical discomfort when SO upsets me?

I (20F) have started noticing that whenever my boyfriend (21M) of 2 years makes me upset, I get a shooting feeling from my mid chest to my stomach. It first occurred a month ago when I was silently crying next to him. It feels really tight for half a second and I feel slightly out of breath after. But it only happens when I’m lying down I think. And it only happens when I’m like in-tears level of upset.

I’ve been more upset in the past over other things (not relating to him) and I used to sometimes get mild tight discomfort in my chest but it’s never moved around nor reached my stomach before. This feels completely new and I’m not sure why it’s suddenly happening? Can anyone else relate?

tl;dr : recently experiencing tight shooting feeling from chest to stomach (while lying down) when upset with boyfriend