Hi. I started running in the Spring and average about 9 - 10k now. This weekend I went for a 9k run but I don't know if I've done something different but my knee is now really sore. It feels tight behind my knee cap and achy. It had been a couple of weeks since I'd done any running but I'm a bit unsure what to do. Should I just rest it and do low impact stuff like swimming ? I'm a bit concerned as I'm doing a 10 K obstacle course in 2 weeks.
Thanks for any advice!