Hi...Since its an ankle sprain it's the ligaments which get injured.Injury to the ankle ligaments causes pain,difficulty in walking and most importantly maintaining balance.Kindly visit a physiotherapist for proper treatment since if the ligament doesn't heal properly it will give rise to recurrent ankle sprain and instability.Also try ice application  twice a day for 15 mins, elevate the foot with pillow while sitting and sleeping which will help in reducing the swelling and also do the exercises which will be taught to you by the physiotherapist.Hope this helps