Why won't my pain go down? My ankle sprained 4 days ago.

Sprain. Are u still walking on the ankle or are you immobilized?
Swelling. You probably still have swelling at the area and it is putting pressure on the nerve. Also you have injured the tendons and ligaments and pain is a response to this. Use rest, compression, elevation. Take some Motrin if no allergies.
Time for eval. If your pain has not improved it is time for a full evaluation and radiographs.