it could still be patella femoral pain syndrome. I find in my practice that the improvement in patients with this condition is very dependant on the quality of the Physio they receive. patients often fail Physio in the community before responding to therapy at the hospital. our physios spend 30-45 minutes per session with the patients where they do observed excercise. there are other potential diagnosis but as your have pain in both knees they are a little more unlikely. the MRI if negative for other pathologies will help confirm the diagnosis.