The first step in seeking care for knee pain is to get an accurate diagnosis in order to eliminate other causes. In particular, the stress fracture (most likely of the tibular) needs to be eliminated. Assuming that the diagnosis of the Runner’s Knee is accurate here are my 2 cents on it.
I agree with rroof comments above (apart from the importance of orthotics). Here is a more elaborate write up on the same thing including exercises for Vastus Medialis.
The Runner’s Knee, or patellofemoral complex(PFPS) is, at least in the first approximation, a direct result of chondromalacia of the patella (softening of the cartilage of the knee cap). This softening is most likely a result of mistracking knee cap during running. The early running guru Dr. Seehan postulated in the 70’s that when you have a knee problem you should take care of your feet. A recent study of the Bay Area Dr. Saxena found that orthotics helped 75 % of the patients (Saxena A, Haddad J, The Effect of Foot Orhtoses on Patellofemoral Pain Syndrome. Journal of The American Podiatric Medical Association ( JAPMA ). Vol 93:4; July-Aug 2003:264-271.)
PREVENTION: In the first place I would definitely suggest orthotics. If you are a light weight runner and/or a mild pronator definitely try to get soft orthotics. They are much lighter and much more comfortable. In the second place, in principle, the amount of running should be reduced. However, your weekly mileage does not seem excessive and this may not apply to you After that you may consider stretching posterior leg muscles (hamstrings and calf muscles) and the Vastus Medialis. For the latter do straight leg lifts (10 sets of 10 lying on the mat or carpet with the other leg slightly bent to take pressure of the back). Also avoid running downhill, and doing activities and workouts that require your knees to be bent.
TREATMENT: In my experience, unless the pain is chronic and mild, the best treatment is total abstention from running until the pain is gone (generally around 2 weeks for me). This may be difficult for runners, but triathletes should consider this is the only way to deal with the problem since they can maintain their aerobic capacity through swimming and biking. It is interesting to note that the treatment for the stress fracture is the same, but the rest need to be longer (6 weeks or so). In practice, just rest until the pain has stopped.