See a doctor. You need to have an examination to determine the cause of the pain.
Consult doctor. Its important to have a physician look at your ankle esp if you're a runner because it can be anything from a sprain, pinched nerve, inflammation, etc. Avoid putting weight on it if that reproduces the pain, but consult a doctor. Also, a qualified running coach can evaluate your gait and advise you about ways to make your running stride less traumatic. Make sure you have good running shoes.