I ran a half marathon yesterday. i have a sharp pain on the outer edge of my foot when i walk. what should i do to help heal it?

Let it recover....: It would help to know just where on the outer edge of the foot the pain is. (Front, middle, back). The main question is whether or not there is a potential stress fracture at play or just soft tissue irritation. X-rays may not show anything at this point, at least not a stress fracture. Rest, elevation no excessive stress is the best way to help the foot recover.

Get an X-ray: to make sure you didn't get a stress fracture of the 5th metatarsal