I Am 71 Year Old And 2 Months Ago Had

I am 71 year old and 2 months ago had an episode of mild bursitis of the left knee that was treated with a cortisone injection. Soon after I went to Mongolia and did several climb and running. I had a second episode for 4 days that decided without taking drugs and with incompleate rest. I am back home and anxious to restart running. I usually run 7 miles 3 times a week. can I restart running or it will better shift to swimming?