Its not her Archilles is it? I fell off a curb once and although I hadn't torn my Archilles I had bruised/stretched it quite badly and I wasn't able to put any pressure on my heel due to it, it got so bad that I resorted to crawling around the lounge as I couldn't bare the pain.
If it's not that, perhaps she's just badly bruised it, and yes it can hurt.
Our kids don't pay for the doctors, although we pay $15 for Conor