My knee has been hurting since June from running. I used to run about 15-20 miles a week and it feels like a lot of pressure. I quit running around August and talked to my doc. He sent me to the hospital and they only showed me pictures of knees and told me I was good to go. My knee would still hurt quite a bit without me running depending on the force I put on it. I got out here to VA and started running again and started running again (you have to unless told you can't by doc -military). All day after I run my knee hurts really bad feeling of intense pressure on the inside right below my knee-cap (left knee). When I go without running it seems to feel better, but I still can feel the pressure, and when I go run or have alot of action involving increased activity with my legs and knee it hurts more. Even stomping on the clutch pedel. My current doc gave me Naproxen 500mG and told me to just exersize my legs more. What should I do? Has anyone heard of this before?

Optional Information:
Male , Age: 21

Already Tried:
I have seen 2 doc's directly about this (military corpsman), and have also been to knee school which was nothing more than them showing me pictures of knees.