65 Year Old Male, Very Good Hea;th 5'11" 190 Lbs

65 year old male, very good hea;th 5'11" 190 lbs work out @ 15 hours a week, weights and aerobic. I'm experiencing intermittent chest pain behind sternum. Pain is very slight ( more like a knot}. Just started within last 12 hours. No other pain, do not remember doing anything that would have caused it. No other complaints. Worth a trip to the ER. PS have had some recent stress causing events with in the last 2 weeks. Thanks