Foot sprain: anyone else ever have a sprained foot that still hurt four months later?

I was in a car accident,my foot was severly sprained and the injury caused a bunion,its been four months and it still hurts....i been wearing an aircast the last six weeks when i first went to the er they said my foot was fine......is it normal for a sprain to take?this long to?heal? Should I force myself to walk even though?it hurts? I can walk about a 100 feet or stand for about 3 hours but then i get pain,my foot is starting to feel stiff so i been gently maging and bending my?toes to regain flexability...im just starting to worry i thought it would be healed by now....