Swollen Left Foot

im 17 years old ( not pregnant ) , Well At Least I Hope Not, Im On Birth Conrtol Pills. I Have A Really Swollen Left Foot. That Just Stops At My Ankle Doesn't Hurt For The Most Part. I Could Walk On It Perfectly Fine, It's Just When I Touch It With My Finger, Like Push Down On It, It Hurts. Its Been Swollen For Almost A Month. Ive Been To The Doctor,And He Thought I Could Have Gotten Gowt? So They Took X-Rays And Taken My Blood, And They Said That Their Was Nothing Wrong With My Foot. But To Make My Swelling Go Down They Have Given Me Some Steriod Pills To Take. Ive Been Taking These Pills For About A Week Or A Little Over A Week And Still The Sweeling Has Not Gone Down. Im Not Sure Whats Going on With My Foot, And Clearly Nither Does My Doctor. So If Someone Has Any Clue At All Of Whats Going On With My Foot Or An Idea, Please Let Me Know ASAP!! Thanks.