Whatt do you this is? Please Help !?!

Okayy. so over christmas break i hurt my ankle at gymnastics, i couldnt walk for a week or so. now i can but it hurts ALOT. sometimes so much that i have to limp. Every morning when i wake up im not able to walk on it at all. it hurts too much. I took about 2 weeks off from gymnastics when it happened. and now im back to tumbling and stuff, im able to do it but it hurts veryy bad. Also it hurtss alot to runn on it. its only a bit swollen and a tad bit bruised but nothing too bad. and when i turn it inward it hurts extremely bad. I wear a brace at the gym but it doesnt help much, what could this be ? im going to the doctor tuesday but i want to know what to expect. Maybe a hairline or stress fracture ? if it is, will i need a cast ? and for how long ? Thanks (: