I would suggest you discuss your questions regarding your knee pain that may be due to patellofemoral pain syndrome with a physiotherapist. Rest from aggravating activities is an essential component of treatment and it may be that your level of activity / rehab exercises are beyond what your knee is ready for. You may be interested in checking out the above link for detailed information on these injuries.

Hope that helps and good luck,

PhysioAdvisor
www.PhysioAdvisor.com.au