Hey man, im going through the exact same thing. I have a almost constant pain in my left upper part of my chest and it even spreads to my right side of chest and down my left arm. Been to 3 ER's, a cardiologist and a stomach doctor. Every time they send me home with anxiety or acid reflux. Im 19 and im really afraid theres something wrong with my heart cause its been 3 weeks since this all started and it hasnt got any better. It keeps me up at night and i feel like i think about it all day( kind of hard not to when it hurts). I didnt have an actual panic attack until about 2 weeks into all of it. I dont know if this helps but im just lettin you know im in the same boat and about a year ago i also had panic attacks that lasted about 3 months where i would wakeup everyday to have a panic attack for hours.
I know this fear is irrational but my anxiety says it's not.