Mr Panic is the master of mimmick.
He can mimmick most symptoms and 99% of them deadly.
If nothing has shown up on your ECG or blood tests.
Then it sounds to me as if you are experiencing the "flight or fight" sensation caused by too much adrenlin.
It is very very scary, but it will not hurt you.
I agree with the others that relaxation, distraction and learning to control your breathing, will help you a great deal.
It takes a lot of practice. but it really does help.
Love, light and Best wishes
Liz xxx
With hard work and determination and all the things you know.
The world is there for you to take. There's nowhere you can't go.
[]Scatty Eccentric & 'Poet Laureate to panic and anxiety'