I think that you should go see a doctor
today. The symptoms you have and the findings on the x-ray
don't tell me exactly what happened, but I can tell you that they are not normal. The area just below the knee is where the patellar tendon attaches to the tibia. This area can become inflamed when it gets injured. If you had an x-ray that showed a bone island, this means that bone is growing where it shouldn't be. This could mean that you just chipped a piece of bone off with your injury. It could also represent a much more concerning process. For example, very rare bone tumors can sometimes present with pain, swelling and a sclerotic lesion. I am also concerned about the amount of pain you are having and the other symptoms. Numbness and weakness down the leg into the foot suggest that whatever happened to your knee is effecting the nerves that run down the leg.
I think you should start by scheduling an appointment with an orthopedic surgeon
. You will probably need some repeat imaging of you knee to figure out what is really going on their. If this is all due to an injury, the surgeon can recommend the right treatment in your case.