feels like I have small piece of glass,on sole of my foot.

I had an invisible splinter a week ago. I squeezed the general area until a dot of blood appeared and was then able to dig it out. Took 3 days to find it though.

Verruca

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?

A plaster and plenty of antiseptic cream eg Savlon, may draw it out.

My money is on foot bath as hot as you can stand it and of at least 20 minutes duration.

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!