My dog wobbles when she walks and she's not eating much. What is wrong with her and what can i do to help her?

My female chihuahua has been wobbling when she walks and no matter what type of food i give her she refuses to eat it. I took her to the vet and he said that her heart and her eyes are normal and she may have an intestinal infection. He prescribed antibotics and she takes them but she doesn't look like she's improving. What is wrong with her and what can i do? She has been like this for a week now.