Sprained ankle while traveling: Absolutely the right call to set up a wheelchair for the airport; it’s free, you just add the request to your reservation online through major airlines like United. For smaller airlines, probably you call the airport. It would have been a long and tiring walk; O’Hare is big.
Allow at least 30 extra minutes; you have to wait for the wheelchair to arrive, and it may take longer to go through security. Everyone has been sympathetic and helpful so far.
Remember to tip your wheelchair driver!