so sorry for your loss, this sounds like parvo virus to me. last year hours after walking my fully inoculated rottie pup on the beach he had severe sickness and bloody diarrioa we took him to the vet who diagnosed parvo , he was on a drip for 5 days before recovering.he said had he not been inoculated and such a chunky pup he would have certainly died.this is a auful illness.