Foot injury? Please help me!?

On Tuesday we had to either run or walk a mile. I decided to walk all 10 laps because I have a weak ankle. I was wearing my brace. After 7 or 8 laps, I started getting really bad pains in my right foot ( the weak ankle one.) I kept going, but finished last because I really had to push myself to get to the finish line. This was the last test of the year, so I had to do it. I wrapped my foot yesterday & today. I have been soaking it in warm water & epsom salt. The pain is on the side of my foot, towards my pinky toe, and my heel. Sometimes when I walk, the pain goes from my heel into my big toe. What do you think I could've done to it?