Until vet opens put her somewhere very comfy temperature wise (if it's been hot where the birds normally are), quiet, maybe with a favorite buddy., all creature comforts close at hand. What temps has your area been having? What temps this afternoon?
If she ate well and was energetic this morning, I am concerned it could be an egg issue or a sudden viral or bacterial issue (had that happen to my Ellie a few years back - sudden extreme lethargy and antibiotic turned her around from what looked like sudden near death - she is fine now, years later).
Is there any chance at all that she was injured by something today?
I would not bathe her when she is this weak, especially if no evidence of a reason to.
If she hadn't been eating well right up through this morning, I would say to administer 3 drops Polyvisol liquid children's vitamins emergently, by dribbling gently along her beak line with dropper, so she swallows on her own and doesn't choke. Stuff tastes like crud so see if by some stroke of luck she'll take a few cut up bits of blueberry or watermelon or whatever afterward. Since she did so recently eat well, the vitamin thing may not be crucial at this time....so I'm almost inclined not to give her this added stressor..
JJ