I can almost guarantee you Chandler has a torn ATFL and from the looks of how he handled it, but it's been torn for a while and he just never got it corrected. It may have been a partial tear leading up to the fight but I bet it's just dangling now. Same thing happened to me in the Army and I had to deal with an ankle doing that shit for over 18 months before getting surgery.
And oh yes, I laughed my fucking ass off at the stool ordeal.