Sternum Popping/Pain/sinking inward. Combat Athelete

[pbarchjj]

Sparing you the too much information. Originally this happened I believe in high school lifting weights. My sternum popped loudly and I was out of competition and stuff for only a couple weeks until it got better. Then there was a similar situation about 3 years ago. A pop then tenderness, and pain when crunched of sitting wrong, deep breaths and drinking/eating too much hurts.
About 2 months ago the same thing happened. Unfortunately I had Grappling competitions coming up and couldn't take time off. I continued to train the best I could and it continued to pop during sternious movements and pressure. I would take a couple days off until it got slightly better then do it again. Now where my lower sternum is, or xiphoid process perhaps has seemed to sunken in and it will not get better. I saw a doctor (not good insurance) and got X-rays but they said nothing was broken. I am worried because it was getting better in the past but now my body has changed (sinking inward near lower sternum slightly) and it isn't getting better. My career and job as a martial arts/grappling teacher depends on this healing. Does anyone have any experience with this, know something that I can do, or a person I can go and see? Thank you