My ds sometimes gets a sore knee sometimes. It clicks a lot. We have been to a physio but she was not sure of the cause. Now going to see an orthopaedic soon. I have been examining it myself and trying a few stretches. We have noticed that when is does a illitobial band stretch (lying down on his back with one leg bent, knee up and foot flat on floor. and the other turned out at hip so that the ankle is resting on opposite knee, it’s designed to stretch illitobial band) he says he feels a stinging pain at side of knee and right across the front of knee. He seems to think the pain is internally within the knee.
wondered about illitobial band syndrome maybe? When he is lying down watching tv and bends and straightens let it constantly clicks . I believe the click stings a bit. But he still manages to play sport.