Daughter with a distorted ankle

One week ago today, my eight year old daughter woke up with her left ankle turned outward severely.  There was no known injury, or accident.  While the ankle/foot looks badly, she is in no pain.  The problem is that she has to walk on the side of her foot.  This seemed to happen over night.  We had her ankle x-rayed, and an orthopedic doctor says they have never seen something like this.  Can someone tell me what could cause this distortion to her ankle, and what advise we might get?

[TC6990]

The x-ray came out normal.  There was no damage found.  Just need some advise as to what could cause such.