Hi. Ankle sprain usually involves ATFL, deltoid and CFL ligaments of ankle. The severity of your ankle sprain determines your treatment. In any case an acute injury with swelling in the ankle would suggest a high grade tear which would warrant to immobilise the joint by a cast for 3 weeks as it takes minimum that much time for it to heal up. In your case pain has gone but you are not able to walk properly suggests that your muscles around the ankle have weakened that usually happens after the injury.

Consult an orthopaedician.you need detailed examination