Suddenly, I can’t go down stairs unless they have a railing. I went to a ball game in the spring. Our seats were in the top row, where we entered from the bottom. Since there was no railing, I had to ask my son to let me lean on his shoulder. Peripheral neuropathy is the apparent reason. I cannot get up from most chairs without using my arms to hoist me.
On the other hand, my ability to do mental arithmetic is unchanged. I can still multiply two random three digit numbers in my head.
Can’t hit the high notes anymore. Had the flu one winter and now I can’t hit the high notes when singing along to the radio. I used to be able to say “snuggle” just like that commercial bear, nope, no more.
I’ve got a weird one.
I can no longer be submerged in water without water going up my nose, causing me to feel as though I’m drowning.
When I was a kid, that was never a problem. I never even thought about it. I could swim around underwater for as long as I could hold my breath. Then, one time, in my early 30’s, I jumped into a pool and water shot straight up my nose; I struggled to the surface and spent a good minute or two coughing. And it’s been that way ever since. If my head goes underwater, I have to hold my nose to keep the water out.
Did some subtle shift take place in my nasal passages? I have no idea.
I’m having the same feeling as well.
Narrow mountaintrails or something are not a problem, but walkway bridges and things are no longer pleasant.
A few years ago we were at a lookout point with grate style flooring on the outside. My son was looking down and yelling: “look how high it is, daddy !”. “Yes, I can see that from here as well”. :o
Stairs are slowly becoming more of a vestibular (?) challenge for me, too. I didn’t realize there might be a specific physical cause (aside from “gettin’ old” 
) – gotta look into that.