[Buster Brown]

Hi and welcome to YT. I am so sorry that you post was unanswered. De matting a coat can be very painful as the mattes can be knotted very close to the skin and breaking them up can pull on the skin plus if they used razors very close sometimes it can cause a burn so the grooming may have been traumatic for your Yorkie. Diarrhea can be very dangerous to our little dogs so I recommend you bring her into your Vet to make sure something is not going on with your Yorkie. Being a rescue she may have fears issues but if she was playful and is now fearful I would wonder. Have you been to this groomer before? Do they have a window where you can monitor what is going on or do you leave her and then come back? The groomer may (or may not) have been rough and if left and they put her in a cage maybe she thought she was being left again. I hope she is doing better but if she is still not eating and has diarrhea please get her to a vet fast! Sending prayers and best wishes.