I purchased a 13 week old persian 2 weeks before christmas. I brought her to the vet the day I took her home. He noticed her butt was a little red, but otherwise she was in good health, had been dewormed and was up to date on all of her shots, etc. For the first 2 days she pooped 3 or 4 times a day and it was diarrhea. I called the vet and he said to give her canned pumpkin and to add metamucil to her wet food and if there was no improvement after 5 days to call him back. It worked, but if I feed her wet without pumpkin or metamucil, her poop goes right back to mush. I changed her food a week after getting her to EVO, which is grain free and haven't seen a mushy stool since. Now this morning, she threw up a little bit, then went to the litter box and had a watery bowel movement. What could be the problem, and what do you suggest? She is due to go back to the vet for her rabies shot around the 20th, but should I wait that long?

I wouldn't wait because she may end up getting dehydrated. Especially since she is a kitten. Just like a baby who that happens too- they can get dehydrated really fast. Good luck! I hope she gets well