Trapped nerve feeling in left breast - what could this be? (photos)

I noticed last year on the underside of my breast where the scar is it isn’t a straight line and looks like it’s bulging out. The last few months I’ve had a feeling of like a trapped nerve. It’s made me unable to take full deep breathes and when I try take a deep breath lying down I can feel a pinching inside my left breast. When I push my breast upwards and in a bit it allows me to take a full breath. What could be going on here please? I’ve had them done almost 4y and had a baby 15m ago!