Hi Melinda,
I was born with mine, it is usually that way, I havent heard of anyone developing it. Mine was detected by a cardiologist prior to having surgery back in 1969, I was 7 yrs old then. It is benign. The more serious heart murmurs, can be corrected with surgery. (My surgery had nothing to do with my heart). I dont get chest pains with my palpations. Panic attacks are often accompanied by palpations, but that doesnt mean you have a heart murmur. If you have had the EKG and holter test done, they would have detected it right off the bat. My general doctor can hear it with just a stethescope, says it just sounds like clicking. I think that is why so many panic sufferers are scared of having heart attacks, because the most common symptoms are racing heartbeats, and the feeling of extra, or skipping beats. Anxiety can bring on the feelings you are having, which unfortuately just feeds our panic. I have found a way to stop the irregular heartbeat feeling, it helps a great deal. Make yourself cough really hard, repeatly when you get them. Or bare down hard, as if you are birthing a baby. Doing this a few times, seems to stop the palpations.
Hope this helps,
Trish