Well, I get them all over the lungs, not just around my heart. I have been told they are plugs coming loose...
Sometimes the pain will last a few breaths, other times just one quick inhale.
I always feel like I "break" them loose faster if they are taking a while by doing quick, fast inhales/exhales...
Im not sure if this is the same pain you are feeling... is it always in the same spot? Might be a big of pluerasly (spelling?) though that is a constant ache for me.
I would mention it to your doc, but it sounds like just plugs coming loose to me, unless it is in the same exact spot everytime, I am not sure... maybe a gigantic plug?
good luck