My mum used to make us soak our feet in a bowl of warm water containing Dett0l when she thought we had picked up glass from the beach. It will soften the skin and perhaps make even a tiny opening more obvious. Worth a try?
I had same. Rang doctor's surgery after couple of days. I said ridiculous to go to a&e but also don't need to take up doctor appointment either. Any suggestions? Receptionist organised for me to see nurse. She sorted it with very bright spotlight and fine tweezers. It was a deep seated bristle. Good luck!