Im only 18 and Two days ago i bend down to get something and when i when I stood back up i had a sharp pain on the left side of my chest kinda under my breast its only lasted a couple seconds but it hurt to breathe then it went away but im still having a little bit of pain it comes and goes and doesnt hurt as bad as the frist time i dont know if this has anything to do with it but my left breast is bigger then my right one not by a whole lot though any ideas of what it is?