Here is a link with good info, in regards to different areas of the foot: http://www.epodiatry.com/foot-pain.htm
I am not a Doctor nor a Podiatrist. So anything I say would only be guess.
Sometimes, tendons are hurt, or could be a nerve. Could also be a muscle strain.
If it continues for another couple of weeks, I would definitely go to a Podiatrist (foot doctor). If none is available in your local area, then I would see a MD (Doctor).
I do wish you the best best of luck.