Scab with a small circle inside the middle

I have looked this up a million times but can’t seem to find anyone who has the exact same thing. There is a random bump on my leg that has been there for maybe about a year or more. After it wouldn’t go away, I squeezed it and it was like never ending pus coming out. After I thought I got it all out it & kept squeezing it was like the bump would start going into itself instead of popping out. After it became a scab I continued to pick at it and noticed that when I would pull the scab off, it would still have this piece in the middle that seemed deep in my skin & wouldn’t come off with the original scab. After picking for weeks I finally got the middle out with a pair of nail clippers because not even tweezers could do it. It left a hole in my skin just where I pulled it out and what I pulled out was hard and basically looked like a little tiny ball of really hard, dried up skin. Kind of like a little tiny callus inside my leg. Anyone know what this is??? It’s driving me crazy.