Tl,dr; Preventative but medically necessary double jaw surgery to correct severe jaw bone deterioration and TMJ issues.
She had years of teeth grinding in her sleep that unbeknownst to her led to a misaligned bite. Earlier this year she started getting TMJ due to that. That pain brought her to the doctor who discovered the bone deterioration on top of that. It required a complex six-hour procedure to reposition her upper and lower jaws, and necessitated a different kind of thicker hook braces for the recovery period. Had she not done it soonish, she'd pass a point of no return, and in 10-20 years she'd be unable to eat hard food with no way to correct it. So she waited to do it until her insurance approved it the surgery and she was out of school.
As for her appearance, she's been on a liquid-only diet since Dec, and will have another month of liquid + soft foods. Her facial swelling should reduce significantly over the next 1-2 months, but won't finish for about another 6 months. To perform the surgery they had to remove some chin as well as cut into her sinuses, so she's had breathing issues while recovering plus adding the braces so they can use strong bands to restrict jaw movement, a la wiring a mouth shut. So with the swelling on both sides of her jaw, her chin, and her nasal area, alongside the braces, she obviously looks different to how she did before, and her face will continue to change for a while, not to mention any weight loss she experiences from the restrictive diet. On the plus side for her, she'll come out with some very nicely shaped bone structure, and more hourglassy than she already was, plus avoid a major medical issue.