Belly button piercing

Okay so I got my belly button piercing 3 weeks ago. It seemed like it was healing just fine, now it has gotten infected and I'm not sure what I'm doing wrong? I've done the sea salt with water soak twice a day, and it doesn't seem to be making a difference? So I used peroxide (yes I know, not technically supposed to use it) and it was pushing all this green pus out so I know for a fact it's infected. I would LOVE and appreciate all your comments on how you got your piercing to heal. Thank you in advanced!