If your reliever medication isn't helping to improve it, I would get it checked out by a GP asap.
I had a mastectomy with recon and have had trouble breathing deeply as the ribs on that side hurt, so I've had a bit of a rattle that the dr could hear when listening to my chest. It's not causing shallow enough breathing for me to feel light headed, nor feeling heavy in the lungs themselves.
As your surgery was not as major, it seems like a big side effect in relation to what has been done. Hence why I would get it checked in case it's one of the complications that are a risk from any general anaesthetist surgery.