You might not necessarily be having an all-out panic attack
, but you certainly are experiencing panic-like symptoms. I have panic disorder and I experience those symptoms plus a few when I have panic attacks. My doctor told me that you can experience the symptoms without having a panic attack.
I would suggest you see an M.D. and have him check you out. It might be your heart, but if it isn't and you are having panic attacks he can send you to a shrink. Either way, you should really get checked out. You really don't want it to be your heart OR panic attacks.. but its certainly important to get either checked out.