I agree get her to the VET ASAP. None of those signs are any good. She was young when you brought her home but thats my least concern. My neigboor got a Chihuahua mix puppy at like 5 weeks and he did fine. My consern is if she has no shots it could easily be Parvo and you dont want that, especially if you have other pets at home. If its Parvo and your girl has it she needs to see a vet immediatly. If Parvo is gone you will need to clean your home as well, the virus still lives inside and if you bring any other pet inside she/he will catch it.

It might also be due to a diet chance? Or treats if you give her any.

I have a 15 month old Scottie. Now i am not sure if she is pregnant we will find out at day 50-55, but thats not my point. My point is that she started to have Diahreah plus a weird yellow mucus on her stool. I took her to the vet immediatly to get some test done and nothing was wrong. Then a couple days later i remember giving her this nasty looking treats, apprently she liked them but they where doing her wrong. So i trew them out and she started to get better. Now the mucus is all gone and she is back to her self. This happend two weeks ago.