diarrhea day 3

We have a Yorkie/Shih Tzu mix dog (1 year old) who has been having diarrhea for the past 3 days. She appears very depressed and isolates herself. She has been dragging her butt and her anus is red and inflamed.
The diarrhea is about the color of golden brown sugar and has the consistency of pudding.

We have withheld her regular food and given her beef and rice at the suggestion of the pet store.

Does anyone have any advice? Is this an emergency?

She needs to go to the vet, we can't diagnose her problem over the internet. She sounds very uncomfortable though, so I would definitely get an appointment for as soon as possible.

Vet, IMO.

It's possible that the inflammation and butt dragging is due to the straining from having diarrhea for 3 days, but I would be contacting the vet since it's gone on for a few days and doesn't seem to be changing.

Vet ASAP. She could have blockage, have anal glad issues, etc. We cannot diagnose her over the internet so please get her to the vet. It is an emergency, diarreah can make a dog dehydrated and they can go downhill fast!