First Running Injury

This training season seems to have been broken into bursts.  First I had vacation where I missed a long run and only fit in 2 runs during the week of vacation.  The day after vacation I had to cut a planned 12 miler to 10.  The following Monday I got sick and didn’t run again until Saturday.  I ran 13.4 of a planned 15, but finished with some pain in my left foot.  The pain started in the last mile and a half.  I am not sure what the source of the pain is, but I am hoping it is just a strained/sore muscle.  It hurts to walk on and needless to say run on.  I am going to try a mountain bike ride this afternoon.  Monday will be a day off and chance to rest or maybe a swim.