I Fell Playing Tennis Last Week. My Ankle Swelled Immediately

I fell playing tennis last week. My ankle swelled immediately and the next day the top of my foot was swollen as well. I iced it. It never hurt. The top of the foot is no longer swollen, but the outside bone has a swollen area around it. I walk fine, I even played tennis this morning. I don't ice it often, but I am wondering why its swollen