For the past few weeks or so, I've been having trouble with my knee. If I run for a long period of time, my knee starts to hurt. If I walk its fine unless it is after running then its hard to walk with it hurting. I also do 30DS which it hasn't hurt it too much. I use a heating pad on it because it seems to help more then ice. I was looking up my symptoms and ran into Runner's Knee and tendinitis. I don't really know which it is and was wondering if anyone on here had any insight into what it could be and what I could do to help it. Thanks!