My dog is hungry, but she can't keep any of her food down and can't eat very well?

She will be turning 16 this July, so i know that it's about her time, but lately she can't keep anything down for more then 3-6 hours...it's like it just sits in her stomach or something. I know we will need to take her into the vet, but is there anything we can do in the mean time before taking her in, since the vet is closed today. Also, I know her kidneys are deteriorating too, so her poop is becoming runny and not solid...we had temporarily solved that problem by giving her special kidney food that we got from the vet, that helped to slow the process, but now since she can't eat her poop is runny again.