Welcome! My name is***** am a UC Davis graduate, and currently, a Medical Director of a veterinary hospital.
I am sorry to hear about this concern for Zoe.
What you are describing sounds consistent with possible vestibular disease.
The most common symptoms can occur in any combination and include: head tilting, walking
in circles, vomiting,
movements back and forth (nystagmus) or the eyes pinned to one direction (strabismus), and/or drunk-like walkingVestibular Disease in Dogs
Generally, vestibular disease is caused by either:
Central disease which includes anything within the brain
Peripheral disease which includes problems outside the brain like inner ear
infections, toxin exposure, organ problems
Or, Old Dog Vestibular Disease. No known cause found on any tests and possibly attributed to having a stroke
Now, for Zoe, I would double check her ears to ensure there is nothing in the canals to suggest a bad ear infection. Also, she will really need a basic blood and urine test to screen for any systemic (internal) issues that could be contributing to the problem.
I assume you have no reason to expect that she has been exposed to any toxins or recreational drugs. But, disorientation I take very seriously at this age, and try to encourage veterinary examination and testing as soon as possible.
When very disoriented some vets will even start motion sickness medication like meclizine or dramamine, but I would wait for the vet exam before doing anything. Good Luck!