I've been getting a pain in my left pectoral area lately? I'm 19, is it normal for me to worry about-?

having a possible stroke? This pain near my left pectoral area makes me paranoid. I can't tell if its an inner problem or outer. I have been working on my pectoral muscles in the gym but the pain feels like its coming from the inside. It's nothing major just a slight pinch. If this helps, I'm 175 lbs and 5'8 and I can run a mile in about 6:30 so I think that I'm in good shape.