heart pain is never sharp, or of specific location. If it's sharp, and if you can point to where it hurts, its not your heart. Its almost certainly caused by chest wall muscle pain, from anxiety. There is a test for this, that you can do at home. Basically, put your hand on your left ribs where it hurts, and move them along your side - closer to your back then your chest. Then press firmly between your ribs closest to where the pain is.
This should cause a strangely large amount of pain until you stop pressing. If it does, then its simple, benign muscle pain.