Hi everyone! I started running a few weeks back with the goal of being able to run half a marathon by the end of the year. I've never run before, and I'm not aiming to run in an official race for now. I just want to be more active. I did a lot of research and reading, and also went to a running store to get fitted for shoes. Things were going pretty well until last week.... All of a sudden, I developed a pain in my left knee -- to the point where it was uncomfortable walking. I wasn't running long distances (about 2 miles per run...still trying to build endurance). I have flat feet, so I'm wondering if maybe I'm not getting proper arch support from my shoes? It's been a week since I ran and my knees still hurt. I do spend about 20 minutes stretching beforehand, and walk to warm up and cool down. Does anyone have any suggestions, or should I go see someone? Thanks!