What Causes Pain Around Knee Cap?

I am a 14 year old girl who plays netball. I have been having knee problems with both left and right for the past 2-3 years. I usually get pains around the knee cap. The pain mainly comes when I'm playing netball when I land. But sometimes I usually get the pains walking to school in the mornings during winter. I have seen countless physiotherapists and they have all said it is just growing pains but the last one I went to said my knee turned inwards. I am just wondering what could be going on?