Hi and welcome to YT I also joined when Buster was seriously ill and I was looking for advice. I got the best advice out there take him to a Vet and I am glad I did it saved his life. I know you saw a Vet but if you think the medicine is not helping and your tiny dog is vomiting and has diarrhea they can become dehydrated very quickly. This happened to Buster and he had to be put on an IV to hydrate him and he was becoming very weak. These are dangerous/life threatening symptoms for tiny dogs. I really don't think the wobbling has anything to do with being messy it is a symptom of weakness not neatness. I would be very worried and honestly would want to take her to an emergency Vet.
I feel so bad for her and don't know how to help
Take her to another Vet better safe than sorry. Sending prayers for your Yorkie. You are her advocate.