Strange leg injury - possibly extensor digitorum muscle?? Need help!

I hurt my leg 1.5 years ago playing floorball (similar to ball hockey, tons of sprinting, lots of lateral motion, and always on the balls of your feet). I have been seeing different Dr's throughout all of this time but have not made any progress.

It all started as follows:

I was training really hard for the World Championships for floorball so I was in great shape, doing a lot of running, long distance, sprinting, and strengthening in the gym. My lower body was very strong with no prior leg injuries. When I got to Europe my sponser gave me shoes that I had to wear and they were to small for me. My toes were so tight in them and were basically curled under my foot. They were so tight that my toenails turned blue and eventually came off. I tried to tough it out and wear the shoes but they hurt very bad. In the third game of running in these shoes (about 45mins in) my left knee on the lateral side started to get sore. Within 15 minutes it went from becoming a little sore to not being able to bend my knee due to unbearable sharp pain around the fibular head. The pain begins in the last 15 degrees of extension. I can not do any activities that involve me being on my toes (running, eliptical, step classes). Doing motions such as skating and biking do not cause nearly the same amount of pain because these exercises do not involve as much dorsiflexion.

I have seen several doctors, a physiotherapist and a few chiropracters who have fixed some of the precipitating problems such as a very tight IT band but I am still having really bad pain at the fibular head.

I have had 3 sets of Xrays, 2 sets of MRIs and a bone scan. All have been focused on my knee. All have come back normal. I am thinking that the problem is not in the knee but maybe in the foot instead. Possibly the extensor digitorum longus muscle? This was a very odd injury as I feel it was caused by running hard with my toes curled under my foot. Any thoughts would be greatly appreciated!!