Hi, I am so sorry you are experiencing this. I, too, have occasional issues like this, for me, it is anxiety related. The more you panic, the more adrenalin is released, this causes the flight or fight response and cortisol, etc, shots through the roof. If you can get an EKG done and it shows all is well, I am sure you will feel lots better.
You can get a doctor to do an EKG if that's normal you will definitely know it's not your heart
another thing is when u touch your chest does it hurt?
it might be panic attacks, try put down sugar and sodas , its help, and go talk to a doctor , they will direct u to psychologist who will help u :) he sooner the better