What Causes Pain In Below Collar Bone After Playing Golf?

Yesterday played 9 holes golf; in theI evening, then again this noon (day later) had mild pain, kinda dull, on r side, above breast but below collar bone. Took twi Asa while ago. No sweating or tiredness, breathing fine, pain came on after eating bowl of popcorn, the briefly raked leaves for about 15 minutes. Girlfriend, ret. RN, took pulse result 72, she speculates hiatal hernia. My bp consistently over the yrs (I m 76,) has been great (120 over 70-ish). Should I be worried?..