cmpa2008,
Numbness is a sign that a nerve is asleep. Contrary to what our mothers told us about a numb foot (after you sit on it for a while) being due to the circulation being cut off, that is incorrect. It is due to the nerves being compressed. When the compression is removed, the nerve will wake up.
So, numbness in the first web space of the foot (space between the great and second toe) is actually classic for compression of the deep peroneal nerve. In some cases, it can also signal a nerve root compression in the lower lumbar spine.
Though the numbness signals a nerve compression, it does not tell the cause or exact location.
It is not uncommon for the deep peroneal nerve to be compressed around the knee or anywhere along its course through the leg. It is sometimes seen in people who have to squat a lot (baseball catchers) or people who wear leg braces around the region of the knee. Anything tight and constricting around the leg can put pressure on the nerves.
Since it is located in such a discrete location (and a known nerve distribution), it is very doubtful to be caused by a systemic problem such as a metebolic problem (diabetes or thyroid problems). These tend to cause a much more diffuse numbness and tingling, in both feet.
If the numbness does not go away, you should have it evaluated by an orthopedic surgeon or a neurologist.
Good luck.