We cannot provide a medical diagnosis about your dog's situation. That is what your veterinarians do, but many pet owners look to the internet to try to find answers when the cause feels unknown.
You could ask the vet about the possibility of other neurological conditions, such as degenerative myelopathy or a stroke (for which you even saw a parallel). Dogs can have strokes. An internet search showed that degenerative myelopathy is a condition older boxers might develop, but seems to affect the spine and hindquarters. You might find some helpful information from the links in the discussion comment below.
You buy a thousand lottery tickets (different numbers) and win nothing. That is statistically significant because the chances of that happening purely by chance are pretty slim. But if the lottery is operated properly, the result is not practically significant. There is nothing that can be done. Tough!
nothing
No nothing is happening
nothing. this is a dream
nothing
nothing
nothing
nothing she is fine.
I'm eating it all! lol!
Nothing
nothing
NOTHING