Sounds like mild entrapment of superficial peroneal nerve - probably where it penetrate fascia which is of variable location. - It would be the upper point in referenced image. https://encrypted-tbn0.gstatic.com/i...16qaNO468dhPUB - Though often more medial. You should find a spot especially tender and might facilitate pain jabs or tingling feeling (a tinel's spot) when active. Injecting spot with steroid might help.