I got my belly button pierced 6 months ago and I recently changed the ring for the first time. I noticed that after a few showers the ring started to discolour (its a dangling ring, so the chain part started to turn brown).
I don't think the ring was surgical steel, it might have been stainless steel and it's kinda irritating my piercing.
I'm not sure if it's a reaction to the new ring or just because I changed my ring for the first time.
metal plating wearing off maybe? What ever the reason, if it's tarnishing and irritating your piercing I'd think it's best to replace it with something of better quality before you end up getting an infection.
I don't really know anything about belly button piercings nor do I have anything helpful to say, but I want you to know that I think belly button piercings are hot. You should totally keep it if it does not cause too much trouble.
It could be a cheap metal, did you get into water right after it was pierced? Or not cleaned properly.
The chain? The part not actually stuck into your skin?
If the chain is turning brown that means that it is not surgical or stainless steel, it's something cheap and it's probably rusting or just generally falling apart.
If the part that is actually inside your body is discoloring then take it out at once, clean the area with anti-bacterial soap and warm water and put in the old one, but keep an eye on it to make sure there's no puss or funky smell coming from the piercing.