The outer side of my left foot has been numb for 4 days, before the numbness i experience pain in my left leg when stretching or rotating my ankle.

Nerve stretching.: The nerve supplying the skin to your outer foot has been either stretched or otherwise injured to the extent that nerve impulses can no longer move down the nerve with authority. Fear not, most times the nerve regenerates and the feeling returns. You will have to be patient. To remove all doubt you can always have your foot evaluated by an expert.