Area below my ankle hurts?

Yesterday I was at dance for 5 hours. My ankle/foot did not hurt at all at any time yesterday. However, this morning at about 8:45 i was at school walking to one of my classes and that area of my foot really started hurting. It feels better when there's no pressure on it but when I turn/ben my foot inwards the pain is very strong right there. It hurts slightly when I walk, too. What's wrong with my foot?