Similar experience, including multiple trips to the ER fearing my imminent death. Still waiting for the bill on the latest one. The first time it happened I had dialed 911 on my phone but stopped short, fearing the impending life-ruining debt it might plunge me into. Thankfully it wasn't actually a heart attack, but the fact that people even have to stop to make a risk assessment like that is dystopian.

As for the symptoms, it is indeed astonishing how "physical" anxiety can be. Most people conceive of anxiety as just an emotional state, and think a "panic attack" is what you have when you're really nervous about a math test and get a cold sweat. The true horror of a real panic attack can't be described to someone who hasn't experienced that level of mortal terror.

And it's definitely true that once the trauma is "etched" into you like you describe, your mind can reconstruct it again much more easily. I find physical sensations that used to be mildly annoying, like a stomach cramp or post-exercise exhaustion, can summon the anxiety right back again.

The scientific evidence for the long-term effectiveness of SSRIs is dubious at best, so I'm attempting a more comprehensive life change to improve my outlook, including trying to build stronger connections with people and community. Isolation is one of the most intense causes of depression and anxiety, among other health problems, so addressing it is a good idea for anyone.