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If allergy testing has not been done, I strongly suggest that be done as well as some imaging of the brain and vestibular system. The unbalanced walk, falling, vomiting, drooling etc can all occur due to disturbances in the vestibular system. Symptoms of vestibular disease include standing with legs spread out, swaying, head tilt, abnormal eye movement, walking sideways, falling over and may include vomiting. This could be due to the ear infections, some medications can cause it and old age. Here are some great sites on this condition:
The good news is that if this is the problem and it is due to old age, the condition normally resolves itself over a few weeks. However, if it is due to the ear infection or a tumor, then they need to be resolved to resolve the symptoms. Now one problem with meclizine is that it will help with the symptoms, but if the vestibular resolves itself, the medication will produce the same original symptoms. I know this from personal experience since I had the human equivalent to vestibular disease and was prescribed this medication.
If allergy testing has not been done, it needs to be so the allergen can be identified and the cycle of ear infections stopped. At this point, oral antibiotics might also be necessary to clear the infection. If the allergen is identified and avoided, then the ear infections should be resolved and the vestibular system problem resolved.
I do believe your dog's behavior is linked to the vestibular diesease, but Cognitive Dysfunction Syndrome (CDS) also produces similar symptoms such as incoordination, getting caught in corners, forgetting who people are. There is a wonderful site that explains it well and also explains how to document your dog's behavior and discuss it with your vet.
The good news is that there is a drug called L-Selegeline (Anipryl (R)) which has been recently approved for use in the clinical indication of cognitive dysfunction (CDS) in dogs.
Please see this site for more information and other causes that may exhibit the same symptoms.
Discuss the things I have brought up with your vet and request additional testing so a treatment plan can be developed. I hope this information is helpful to you.