I just had my knees looked at last week actually. I have “anterior knee pain”. In other words the fronts of my knees can hurt with downhills, biking, and impact. I was given some excercises, but also some stretches. I’m surprised that no one has mentioned that. With these problems it can have to do with the hamstrings not being flexible enough and the quads not being strong enough thus the tendon below the patella (kneecap) tracks up and down out of line. At least that’s what I understand.
I was given two simple but VERY important stretches- a basic standing quad stretch where you pull your foot behing you and touch it to your butt. For your hamstrings, lie on the ground, bend one knee towards your chest and then extend it upwards while pulling the leg towards you. Do both stretches to 15 counts at 6-10 sets, twice a day. That’s what the doctor told me. That’s also the what he said about the excercises.
Also important is the way your foot is supported. Definitely get Superfeet. I use them but my orthopedist is going to look at getting some kind of wedge to make my Superfeet even more super (supportive).
Good luck. 
zach attack