That one is a tough call too. It's not unusual to bruise a bone or otherwise damage it in almost undetectable ways. While the shafts of the bone are hard (Pick3 in 3... 2... 1...), the ends of bones are more like balls of mush. They can receive blunt trauma and while they feel like a break, don't show up on X-ray. Using a walking boot is pretty standard for someone presenting with ankle pain and a negative X-ray.
Remember too, I don't know shit about your situation. I just have a lot of empathy for doctors because it's a constant struggle over how much testing and treatment to do.
Regardless, I hope she gets better soon.
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