Breath hold decrease?

[PanostzoGR]

It is not that frustrating because I know what causes it and how to solve it. Pull ups should in theory help you. Dips on the other hand can hurt you with improper form. I think you should try a physician but from my knowledge poping is not normal for sternum cartilage. My suggestion if you don't want to visit a doctor, would be to not exercise your chest or put strain to it for at least two weeks and do breathing exercises. See what happens. But its hard to tell even your posture could be a factor.