What Causes Breathing Difficulty And Audible Popping Sounds In Ribs After Injury?

Hi! I fell backwards into a table 6 days ago and hurt my ribs. They have been incredibly painful and breathing has been very difficult. Painkillers did little to ease it and a&e said poss fracture. Then on Wednesday (4th night after doing it), there was an audible popping/clunking sound and breathing became very difficult. It was incredibly painful and I could raise my voice no louder than a whisper. I could hardly move. The next day was v painful but then started to ease by early evening. It has got better since and now taking a deep breath is fine. I now feel sore rather than totally broken. The stabbing pain has gone and so have the muscle spasms. If I do too much activity it hurts but nothing like before. What was the clunk? Could it have been a break realigning? Or, air pocket? The pain is on the outside and just under and below my left breast but not near the sternum.