YES. Many of us have had that feeling. I remember the first time it really felled me (I was 18 then, am almost 62 now...and it occassionally occurs...but meds help, as does exercise, woods, water, and photography...)
It went on for years, and there was no "Panic DO" diagnosis (not to mention the PTSD et al)---I knew intellectually that I was physically healthy but also "knew" I was about to die. There came a time, during nursing school, when I wanted to put a piece of paper in my pocket saying "Don't think I didn't suffer"...in case I went down. I also used humor (I had a rating scale when my kids were young, and the dx did exist, that helped me----)---it is an Awful feeling. I did not have the palpitations with that feeling (or the usual "anxiety" symptoms)---and I was considered a very calm, self-possessed student and worker...
Do tell T. She will be able to help. This really is a biochemical reaction in the body that gets triggered who-knows-why, it turns the flight/fight response up so high...and then it begins to self-trigger, sometimes we connect the triggers with certain events and develop avoidance, and phobias...but it is like a switch that is turned on till it goes off. It is "out of nowhere", at least initially; and we want to explain it---------------------we are human and want to be able to say "see this mark, I got stung..." or the equivalent...
Lots of help out there for this now, and a good time to get it is EARLY ON!!!!!!!!!!!!!!!!! best luck, hang in there.