Knee problems due to breaststroke (patella femoral syndrome) help!?

I'm a breaststroker for my high school swim team and also swim club year round. Recently I have been having knee pain and went to a knee doctor and he said I have patella femoral syndrome, but I don't have a severe case. I've been doing my physical therapy and went back to swimming. I have been doing mostly free and back, pulling, and a bit of butterfly. I am not aloud to swim breastroke for a while and I fear that when I can I won't be as fast as I used to be. So is there anything I can do to help strengthen my breaststroke without doing the actual kick?