I've had serious balance problems and what is called 'prioperception' [essentially, how your nerves aren't sending the correct signals as to where you are and are going].
Ask your doc, also ask for recommendations of physical therapists [they get feedback and usually list accordingly]. My neuro and other docs have NEVER said I can't have it. My insurance covers a lot of it but it's limited to a number of sessions per year.
Web up ankle sprains, one good site is
www.thestretchinghandbook.com but there are others with better graphics. The key is to learn how to do these exercises SAFELY at first. After that you'll find that there are ever so many steps you can take/do that will help you keep yourself upright the way you want to. You re-build strength and re-learn safe walking at the same time.
My last round of PT was for one sprained ankle & a broken foot [both feet] and I'd been off them for 6 weeks. After that round of therapy I was better overall than I'd been since before PN onset! Before I'd started the therapy, I felt I could have used two canes to get around in one piece....I now have 4 pieces of equipment [under $100.,] for home use: theraband {$10}, stretching bands{$15}, balance discs{$30} and an exercise ball{$30} . Most of the workout [not hard really] is resistance and lo-impact, and much safer overall than other options. Just start slow!
Hope this helps - j