If she’s gone flat like this, I’d want to know what she’s eating, and drinking, and how much she’s sleeping. And since she’s a girl, I’d want to know what her iron/ferritin levels are.
For instance, could she be skipping meals, not drinking any water, and only sleeping 4-5 hours a day. It may be on vacation she got back to three meals and 8+ hours of sleep.
Worth a few questions.