I have a popping sound right between my breasts that sounds like maybe when you pop your knuckles(that's the only sound I know it sounds just like), but it feels like a sharp knife between my shoulder blades now.This happened just from a simple stretch when I woke up one day, and now, it won't stop popping. I don't know if it's related, but since this strange "popping"in my chest started, I get feelings like a bee sting under my skin or maybe like someone is sticking me with a needle!! I am having a hard time really explaining so it makes sense, but that's the closest I can describe how it feels. Thank you for listening.