http://www.wisegeek.com/what-are-knock-knees.h tm
You might find this website 'above' useful I dont know. I do know what you mean when u describe what you suffer with I remember at school as a child nurses came into the school and in 'PE' lesson, we had to walk in our knickers back and forth down a corridor pare foot so they could check our legs and knees were straight.
I shouldnt worry about the doctors just be prepared to walk up and down in front of the doctor and most likely someone else they will send you to see who is a specialist.
So wear your good underwear and a long top, as you might be asked to walk with you pant off you see, so they can see you legs properly.