I have just started running after a five year break. I did a lot of running in high school but after graduation I took more of an interest in biking and volleyball. Lately, after running three miles, I have felt a slight pain in my left upper thigh. This usually happens at around the three mile mark and goes away after my cool down and stretching. I do want to increase my running distance to more than just three miles. I have not felt any pain while biking or in any other activities I do. Any ideas on what could be causing this? Katie23