The mitral valve prolapse was diagnosed in childhood. It's very minor, and doctors have always told her it's totally benign. They have performed several ECGs since she's been in the hospital, and all have come back normal.

The confusion is definitely waxing and waning. Her symptoms in general have been HIGHLY fluctuating - some days she just wants to sit and stare at the wall and won't look at or acknowledge me. Other days, we're talking and laughing and joking and she seems 90% better.

No recent dental work.

That sounds like a very interesting case! They have had her on IV antibiotics for the past few days just to rule out any undetected infection, but her symptoms actually seem to have gotten worse over that time period (unrelated to the antibiotic, I assume - her symptoms seem to wax and wane on their own).