I Am A 68 Year Old Male And I Am

I am a 68 year old male and I am retired but work part time three days a week. I average between 3-1/2 to 4-1/2 miles walking on those days that I work but the last two Saturdays at the football games I have had right side chest pain while walking to the stadium. When I get to stadium I have to walk up many steps to get to my seat but I don't have any chest pain then. I have had this happen off and on for three or four years but not lately until now. Please give me your thoughts!