Panic attacks can come in many forms..

The ones you are having sound just like the ones I had when I started having my own panic attacks in 2001... My chest would tighten and I would feel like I was having a heart attack.. I went in and had all of the test done that you are getting done and nothing showed up on me..

My pdoc said it was and is a panic attack..
He put me on Lexapro and it helped very much..
The meds you are put on my be differnt but trust me relax.. IT will all turn out for the better ok.

Try looking up panic attacks on line to see if any information you find might help.. I think Doc has some posted on this site ok.

Good luck keep usposted ok