I have always felt something hard deep in my belly button but has been to far down to see, however today I used the magnifying feature and light on my webcam to look inside. As I did I saw a piece of black nylon looking thread and a small black ball, I'm presuming this is a stitch however I have never had any surgery what could this be please

If me, I might put Neosporin Type medication in belly button, maybe a bandaid over it, then later in the day take a look.
I only Played a Doctor.
Better advice may follow.