What is wrong with my ankle?

okayy well this mornin i was walking down the stairs with a big mirror in my hand and as i got to the bottom thor(my kitten) started biting my feet so i kinda jumped up and really smacked my ankle hard of the mirror! i dropped to the floor shouting that it hurt and my mom just ignored me and carried on being on facebook :| anyway i can walk fine on it but it hurts when i touch or kinda lean on it and it is defo swallen compared to my other one wha is wrong with it?