Thank you both for the responses!
The vet agreed it's likely SLO, so we're starting with Doxycycline and Niacinamide and might add Steroids if needed. She's in a substantial amount of pain, so she also has pain meds. We're also dealing with excessive bleeding from the broken nails and are going to add Aminocaproic acid for clotting.
It's been a very upsetting experience, so I'm glad to her your girl made a good (if long) recovery, kudzu.