Diarrhea and vomiting with white worms, still the same after dewormer, now can’t stand or meow

Diarrhea and vomiting in a cat may be acute gastroenteritis, panleukopenia or parasitic infection. White worms in stool mean internal parasites, but panleukopenia may also be present, so deworming alone does not clear it.

When the cat cannot stand, cannot meow and arches its back, it is weak and dehydrated, a critical state that can be fatal without prompt hospital care. First keep it warm, give glucose water for strength, then rush to the vet.