What is this in my nipples?

I have these white sometimes yellowish white things in my nipples and i never found what it was online. I'm not lactating, i've never had a child. Ive noticed this for most of my life and it kind of distressed me because i feel like i cant clean my nipples properly. Sometimes soap would dry up in the cracks of the nipple and areola so i stopped directly applying soap there so it cleared up but i still have these string like things in my nipple and they hurt to pull out sometimes so i use nippers. They are not bumps or pimples or anything.

Can you help me identify this?