Pretty much everytime I exercise, I experience pain in the left side of my chest. I don't know if it's my heart, lungs, or muscles etc, but I know it's annoying. I check my blood pressure when I experience the pain and it's perfectly normal and so is my heart rate, so I don't think its my heart. Anyone experience this or have any clues as to what it is? Edit: I forgot to mention that it is usually accompanied by some shortness of breath. I'm 20 years old, 6'3" 200lb.