What Causes Pressure In Chest With Numbness On The Left Side?

Q : Alright im not sure if I had a heart attack tonight or what, but im really worried. I was walking to a bus stop with a few of my friends at about 7:45pm-it was cold out and the ground had about 6 inches of snow. It must have been 36-40 degrees(not sure, thats a really vague guess...all I know is it was COLD). We decided it would be fun to try and run through a meadow to the highway, well we all began running for about 35 seconds. When we stopped I had a really hard time catching my breath-I couldnt make full breaths and my heart was pumping very fast and very hard. I was in a store buying something (right after meadow-store is next to meadow) and I still didnt have my breath back, for some reason putting pressure on my heart helped somewhat. I was at the checkout counter and suddenly my left arm and the left side of my face got really numb, I got really dizzy and light-headed and my breathing became even harder. I walked to a bench as fast as I could and lied down for a few minutes, I felt okay when I tried to stand back up, and I can breath again-but not big breaths. Whenever I take a big breath my chest stings and I have to cough. My chest is still really sore! Im 17 years old, 5 11 , and about 189 pounds. Im a little overweight but its not bad. I have been going to the gym regularly for a month and a half now and doing rigorous cardio exercises. I have a hard time believing it s just because im out of shape... ...im really worried. ...Did I have a heart attack? Does this need a doctors attention(immediatly?) Sorry for the long post! thanks