How To Treat Chest Pain Observed After Sports Activity?

i played basketball last saturday after that i fell muscular pain and after 3days i played again basketball and im having a chest pain since after playing 3hrs of basketball, when i try to run again i feel pain the in my chest and when i press my chest i feel the pain like a bruise, note that since last 3yrs ago i didn t played basketball. thankyou hope you can help me