What are possible knee injuries from a car accident with numbness as a symptom?

I was in a car accident on Tuesday where the inside of my left knee hit the steering wheel column. I went to the hospital and the x-rays found no breaks. I know it's only been a six days, but what's concerning is that there is a big section around the impact sight (about three inches wide) that is totally numb. I tried taking a pen and poking all around it and across it, that section is completely void of any feeling.

What could cause that? Should I see another doctor, or give it a few more days? All things considered, it doesn't hurt that bad. There's some strange pulling inside when I move it sometimes, and when I don't have it wrapped it doesn't like to work (feels like it suddenly becomes jello).

Any ideas?