Glad she's home and relaxing. I was wondering did the vet consider the possibility of allergies to dust/pollen? Wait, rather than sneezing and coughing those allergies can sometimes make you dizzy, which would affect Giada's walking, despite her ability to keep going. Here's an article I found about it. There are more you might want to look up and see what your allergists say about it.
Allergies and Dizziness
Are you feeling dizzy? One symptom of allergies can be dizziness.
www.healthline.com