My chihuahua Bella did that after her first set of shots. She stopped eating and playing after the shots. And I am not trying to scare you, but all the things you are saying in your first post, sounds EXACTLY what I went through with Bella. I took her to a couple vets and they told me she was hypoglacemic (spelling?? ) and her blood sugar level was at 25 which is EXTREMELY low for a dog, they can go into comas when its under 90. Anyway, she was probably hypoglacemic because she quit eating. So...this lasted about 4 days and she didn't get any better and she passed away. I don't mean to scare you or anything, but it sounds like the same thing and they told me I couldn't do anything else for her

Good luck, you will be in my prayers and I am hoping that your chi will feel better!!! You can talk to me anytime you need to
Jamie