I am a 12.5yrs old girl. I have a falling incident yrs ago. I fall on my knee cap and it was not so painful. That was a sharp pain that stops and comes again and continues. I thought it was nothing. But since that incident, i had a slight dent in my knee cap and when i accidentally hit that part, it hurts. Sometimes when i play sports, and i stopped to sit down, and i stand up, it caused pain too and it hurts more than the knee injury i got yrs ago(only this year). My right knee is fine...