Well, without an evaluation it would be difficult to identify the
cause of
knee pain in your case. Possibilities include chondromalacia patellae, tendonitis, bursitis, fractures, patellar dislocation, injuries to the internal knee ligaments/ menisci, infections/ inflammations, arthritis, cyst formation, bone growths/ tumours, nerve injuries etc; just to name a few. I would suggest consulting an orthopedician for an evaluation and appropriate management.