Regarding the "fix" this chapter, in my experience the doctors are likely to miss it and send her home to die, though pretty likely she'd still be in the waiting room when it happens cause ERs are slow if you don't look like you're dying right now. They aren't going to run a CT or MRI just cause a girl hit her head and fainted unless someone rich waves wads of cash at them, they'd just observe and probs put it down to low blood sugar or anaemia and get her out of there cause they've got 6 mangled bodies from a car accident coming in, 3 or 4 drug ODs, 7 assault victims etc that all look higher priority.
Regarding this new body, my money is on the girl is getting beaten/raped at home so lashes out at school.