What to do if a high ankle sprain hasn't been treated ?

Depends on how long: The high ankle sprain can be a signficant injury, sometimes requiring prolonged protection, physical therapy, or even surgery to get the best results. If one happened in the distant past and you are doing well now, I wouldn't worry about it. If it happened more recently (in the last few weeks) or if you are having continued problems with it (swelling, pain, loss function), then you need be seen