I'm having chest pain and i dOnt know why?

I am 14 and im having uper chest pain. Its not my breasts. Its like inside of my chest, above my breasts. I dont know what it is. And i've been having it for a few days now. The only thing i've done latley using my upper chest is this machine at the gym the works your pecks. Maybe i over did it? Its not sore. Its pain. Could i have pulled somthing? Or do i need to go to the doctor?