Why is the top of a new belly button piercing - done with a barbell - sinking into the piercing?

It sounds like the barbell is too short. Go see your piercer asap as they may need to lengthen the barbell to allow for more swelling.

When i had mine done, the same happened. This was because the top ball made an indent into the skin, just as though you sat on a beanbag it sinks to your shape. If it isn't painful then this is the problem. i hoped i helped =] X