Thank you for your question,The best is to consult your plastic surgeon. seeing that you are only 2 weeks post op it is normal to experiance pain as you are still in your recovery early stage you need more time for recovery from 3 to 6 weeks for the pain to be normal.
Please see your plastic surgeon to diagnose the cause of your breast pain. It is unlikely that wearing a sports bra would cause this problem.
You should check with your surgeon as only your surgeon would know the exact procedure performed and your medical history.
It is highly doubtful that you have done any damage wearing your sports bra. Have your surgeon examine you regarding your pain.