Well friend, The weakness, and pain in your foot could both be cause by a nerve root problem. "Sharp pain" is usually a sign of a nerve being compresses/irritated the outside part of your foot is the S1 nerve. this nerve also controls the Peroneous Longus and Brevis on the outside of the foot they control your foot moving to the outside. Also if you have problems walking on your toes because of the weakness this is also a sign of an S1 nerve problem. I recommend seeing a chiropractor for this as they have the most experience with nerve root problems because they deal with the spine.