Why there is bone lump under my ankle?

[1sarah1nazri]

Last year on september, i sprained my ankle while i was doing my activities. I thought it was not that serious because it only hurt to walk on the first and second day. As the time passes by, i noticed that my sprained feet will hurt if i walk to long and i noticed this lump below my ankle. When I touched it, i felt like the lump was a bone sticking out because it was hard and not soft and if i apply pressure ,it will hurt...I told my mom that I sprained my ankle on the first day but my mom seems not to care so i think it is not a serious situation . But in this condition ehat i should do?