It seems like you had an ankle sprain
from the injury
. It is been 3 weeks now. I hope you applied ice packs to the affected area initially.
You could use an ankle brace or crepe bandage for a while until the symptoms subside. It is better to get an x-ray of the affected ankle done as well, to rule out any hairline crack.
Simple analgesics like Tylenol
should help you with the pain.
Get well soon.