My knee caps have been clicking for the past 3 weeks and when avoidable they click on their own when walking, I'm a teenager, what's happening?

Patellofemoral Syndr. Pf syndrome is the most common cause of non-traumatic knee pain (and clicking) and is especially common in young females. It is caused by an imbalance between the knee hinge and the muscles of the thigh, the quadriceps, and often develops after a recent period of increased physical activity like sports. Fortunately, it's easily and effectively treatable with physical therapy so go get some!