this is exactly what happend with me in exactly the same trick.
it happend last day when i was in turkey,its like 2 month ago soon.
i haven't recovered fully from it yet, iam guessin that my leg should have a week more to rest.
you most likely pulled a scene and its infected.
for me the pain is/not in the knee itself but on the right side of my right knee.
my advices is. go to doctor and she will give you a cure for one week, its most likely not enough,beacuse its a serious damage to your scene.
after the week of the cure i went back to doctor and gave me a shot with kortison in my scene and 1 more week on this pill cure.
for me its getting better every day.
advice,,,, dont freestyle before everything is good again.
1 wrong turn in upper trying to save the ball or some shit and you are screwed, take it from me, i tested to see i only upper worked, it didnt!!!
rest my friend,anything else is stupid.
i had so much pain with it.
peace