Patellofemoral pain syndrome (PFPS) is a common cause of knee pain, especially in athletes. The exact cause of this problem is unknown so successful treatment is sometimes by trial and error. What works for some people, doesn't work for others.
Some simple but effective approaches include taping, bracing, and strengthening. A physical therapist or athletic trainer can help your daughter find what works best for her.
Some athletes try everything at once in an effort to control the pain and stay in the game. Others prefer to try one thing at a time and then combine treatment if none of the individual treatment methods work.
Recently some studies were published advising the need to strengthen the hip muscles to help overcome this problem. It seems that weak hip abductor and external rotator muscles may cause increased torque on the knee. Whether this is the cause or the result of PFPS is under study.
There's general agreement that a rehab program targeting hip and knee musculature can't hurt and will likely help.