Is it my high heels...or my cycling shoes

Here's a question, today I took the polish off my toes, my toes are never naked (or without polish) I noticed that both my big toes, the toenail has become recessed in the corners, equally on both toes, so has to be something i'm wearing. My toes are still pink and healthy, no bruising, they don't hurt. I do wear heels almost every day, or pumps rather. I've never noticed this and i've been wearing pumps for a long time ie Madonna era. I've only been clipped in since April, and bought a pair of Bontrager mtn bike shoes (yes for my road bike, i'm too chicken to get the slick road shoes) and spd cleats.

Question is, could my cycling shoes be causing this problem with my big toes? My running shoes are size 9 (which were fitted at a pro running store) and my lbs put me in 8 1/2 cycling shoes.

When I search the net I come up with runners losing their big toenails but nothing on cycling and toes.
I've already decided to stop wearing pumps to work for awhile.

How do your feet feel in your bike shoes? Can you wiggle your toes easily? Do they feel cramped or shoved up against the end of the shoe?

The main problem I have re: cycling shoes and toenails involves my fourth toes, next to the pinky. They complain first if my nails are too long. But I had both of my big toenails narrowed years ago due to repeated ingrown problems.

I wouldn't rule out running. Not necessarily a problem because of the size of the shoes, but my toenails have been squished in like that on the outer corners since I started running years ago. I think it has to do with the pressure when you push off (but I have no scientific proof of that). Make sure you cut them more square than curved, or they can end up ingrown.

I have similar shoes and I am confident that they fit properly. But even though I have been running for more than a year it was cycling that gave me black toenail.

I think honestly that cycling shoes do require you to keep your toenails short. If I let mine get long AT ALL I have that issue.

I have been jogging a lot more lately and have had the same problem. Every time I increase my jogging due to an upcoming race/event, I notice that I have the same issue. Once the event is over and I lessen my miles it usually grows out and is fine. Then when I increase the intensity again it happens again. I just keep them painted and shorter and nobody can see it.

Nice to know I'm not the only one.