It's on the outside of the heart --- you have the heart itself, which is a muscle, then you have 4 chambers which are insdie of that muscle.
But you also have a membrane covering the heart -- my husband is thinking that a pellet lodged into that membrane and caused the inflamatory reaction -- foreign object in membrane.
He can't be certain, because all I am asking him to do is translate and interrupt what we're all hearing.
That's what it sounds like to me, also, except that it doesn't explain the "moved" comment. A pellet wouldn't just start migrating through tissues and membranes a couple days after the fact.