Help with 3 week old French Bulldog puppy

Hello...I have a 3 week old today French Bulldog puppy. She's the biggest of the litter and has been a wonderful eater and very active until this afternoon. She's refusing to eat, very lethargic and is drooling?? She's quietly whimpering... any ideas of what could be wrong with her? I just administered subcutaneous Fluids and attempted to bottle feed some electrolytes with no luck... she's currently in the incubator staying warm. Her rectal temp was 98.7

Hello!  This sounds like an emergency of the type you should take immediately to the vets.  It sounds as though the fluid may need to be in the veins rather than under the skin and appropriate antibiotics administered.  Best of luck