Could this possibly be a symptoms of heart problem

i'm a 17 years old student from the University of the Cordilleras, in baguio, i sometimes suffer from chest pains, on the left side and sometimes from the center,, its very painful, and sometimes i have problems in catching my breath, like i'e been running for an hor,, in reality i was just sitting,, before i don't get tired quickly ,, but now just walking 20 steps i feel so exhusted,, why???