I know this is old and i'm sorry I didnt see it before. Hopefully you will be back sometime soon to check up on your question.
When a piercing rejects, most of the time it will reject again if you get it re-pierced. Sometimes there are just certain areas on your body that dont want a piercing there. I've never had a piercing reject, but I have seen other people's piercings reject and when they try again, it rejects again (usually).
Now your belly button is a very sensitive area to get pierced and the slightest thing can cause irritation or infection. Bending (like you say you did), shirts getting caught on it, bacteria (there are lots of bacteria in this area), certain metals...I mean a lot of things can cause this piercing to get "angry". Now if your mom wont let you get it again, just let it be. If she will, then try one more time and if it rejects again you know its not meant to be.
Good luck and I hope all goes well.
