Why is my pinky toe black and brittle?

It's been like this for as long as I could remember, also my big toes a scratchy looking. I've always been insecure about my toes. My boyfriend has never seen my feet with out nail polish on. I don't wear nail polish all the time and dot get my feet done all the time. This summer I've only been to the nail salon twice.
Why is my pinky toe black and brittle?
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