For the last few days I've been having a problem with pain in the lower-left part of my head/neck, right where my pulse can be detected, whenever I engage in strenuous activity. It always goes away when I'm in a relaxed state. I've also been feeling SLIGHT discomfort in my chest. I'm 22 years old and in really good physical shape, so I don't think I'm at risk for a heart problem, plus my resting heart rate is about 80 so I think that's normal, but I'm worried nonetheless. If anyone could shed some light on this it would be greatly appreciated.