Thanks for writing in.
In your case, it seems that a nerve
has either been injured or compressed which is leading to sensory loss in your knee. I would want an Xray of the knee joint to be done so that we can pick up a hairline fracture
and an examination to be done to rule out any other nerve injuries that you might have missed. I think you should see a physician, although this should get better on its own, if you have no other issues.
Hope this helps