3 Nights Ago I Fell Down The Steps And My

3 nights ago I fell down the steps and my right ankle on the outside whacked each wooden step as I went down .There's no bruising but it looks a little bit bigger, it's hard to tell cause its my bad ankle that I've had surgery on in the past. The pain was excruciating that night and in the morning, I've been using a wrap on it and the pain has gone down as long as I don't walk on it too much. When I'm on my feet for a long period of time the pain kicks in and I start to feel nauseous , do you have any suggestions of what might actually be wrong with my ankle