It’s possible your dog is suffering from vestibular disease. Symptoms include standing with legs spread out, swaying, head tilt, abnormal eye movement, walking sideways, falling over and may include vomiting. There are a few things that can cause this condition such as an ear infection, some medications and old age. Have your Vet check your dog for this condition.
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. Your vet will most likely prescribe dramamine or bonine to help with the symptoms. You can read about dramamine and bonine usage, precautions and dosage here:
Now lyme disease can cause some unusual symptoms including lameness that switches from one leg to another. You can read about that here:
Now vestibular disease seems the most likely cause, but be aware that organ failure can cause disorientation as well and she is old enough to be experiencing organ dysfunction. Poisoning could also cause similar issues as well. I'd try and get her seen tomorrow and have your vet do a quick check. Be sure and mention vestibular disease to the vet. Some vets do miss this.
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