@dadpad,
Oh, I've been there. Even had a thread on it, and chased around the web.
Alas, I forget what happened, except that it is gone.
(I have a bit of a goosefoot spine in my index finger as we speak.)
I also had similar, I suppose a thorn, grow into a granuloma years ago. The doctor rolled his eyes, and he was a friend.
But metal, I've never undergone a metal shard. I am supposing it will grow out if you don't push it inward.
My mother in law used to put ammonia on such things.
Not that I recommend that,