Is it this at 15 years old?

I was sick last week with a variety of symptoms that I think was mono...I had a blood test....but that's not my point...I have had chest pain, a little bit of left arm pain, a little bit of upper back and neck pain, some lower jaw pain .....I'm 15 years old , 140 pounds and 5 feet 4 inches and I don't have a very good diet...I take pills for acid reflux cuz I get it ALL THE TIME....I just can't tell if this is acid reflux or a heart attack....that's my main question.....which one is it? Thnx