Recurring Incident Of Elbowing In Chest, Get Pain And Mild Cracking Sounds On Turning. Sternum Fracture?

Hi, I was elbowed in my chest during a game of basketball. It hurt a lot and it was difficult to breath and i felt very weak. I also had difficulties getting up from bed the following couple of days. After I went to a doctor they said I was fine after running some basic tests such as breathing and stretching . A week after i was elbowed in the chest again during basketball. The same symptoms came up however over time they went away. Now its been roughly over 1 month since the second incident and when i turn it aches a bit and i can hear slight cracking sounds but no severe pains. Did i break my sternum or fracture it, what should i do?