The doctor has tripled my dose of gabapentin to 300mg, 3x a day. I'm still getting facial nerve pain when the stuff wears off.
The dentist's office called me about the situation. I explained. They checked with the dentist, who said she'd "bruised" a nerve and I'd just have to wait for it to heal.
As for my appointment with her tomorrow, that's pretty obviously cancelled. They're going to call me next week and touch base with me about the pain - if it's gone, we'll reschedule.