milu has been having diarrhea the last few days and she puked this morning

. she has an appt. to see the vet tmw. i started giving her can pumpkin, yogurt, and pedialyte yesterday, and her poop this morning was firm. but then had diarrhea again later. (i think the pumpkin is working, making her poop firm)
what should i be feeding her food wise? and how much can pumpkin, yogurt and pedialyte am i supposed to be feeding her?
if she doesn't have an appetite, is it better for her to not eat and fast, or should i entice her to eat something.
milu is 15 months old and 3.2 lbs.
thank you.