you might try putting fluids sub-q in it but it may be too late now wish you had posted sooner .. I use a product called re-sorb for calves it has glucose plus vitamins and electrolites that you mix with water [ to bottle feed scouring calves ] but I use it sub-q in sick pups . the dehydration and secondary infections that set in are what usually kill the pups . anti-biotics and re-sorb has pulled many a critter through some tough times . this sounds like classic coccidiosis . did you give the puppy shot that contains the corona vaccine ? sorry for you troubles and stuff like this truly sucks .
I am giving sub-q fluids she's on genamicin and another Antibiotic. I thought she would be dead by now the way she was acting last night.