Today as I was walking towards a pharmacy, I suddenly thought of the gait.
Once in my lifetime, I was prescribed something that caused mild neuropathy. Not the drug known to cause it, even, but go guess... It went away as soon as they changed it. I remember this typical "gloves and stockings" numbness and while in general, mild, it was rather unpleasant. But I remember that the gait slightly changed, as we depend on our proprioceptors. I wouldn't be surprised if it looked slightly like that person's one.
Now, there are so many things that can cause neuropathies.
Peripheral neuropathies can have a wide variety of etiologies, including but not limited to, metabolic, nutritional, infectious, and autoimmune. These causes
now.aapmr.org
The list itself is interesting. See how many of these meds are cancer-related? These would be something unpleasant but impossible to stop.
Alcohol - but for some reason, I am not sure the person is an alcoholic. But if they are, interestingly, disulfuram (antabuse) causes neuropathies, too.
Some HIV drugs are on the list.
Antiseizure and cardiac ones I put lower because they are usually interchangeable or replaceable. (Although, one of them, topiramate, is so widely used for everything these days that it should be considered. Another thing we often use but forget about its side effects? Minoxidil for hair loss).
And of course, diabetes can cause neuropathy, and it is probably the first thing that should be mentioned.
I suspect that the person either didn't realize that they were taking something causing peripheral neuropathy, or maybe, the condition was such that the medication could not be stopped, think cancer.