How do I remove potential staining post braces?

Hello I've been wearing braces for 2 years now and one of the brackets is moving so the glow behind it is showing and I can feel how rough it is , the problem is that I just noticed a very tiny brown/black spot around the glow not sure if on the glow or around it but it is only one and I don't feel any pain I'm really concerned , is it a cavity or just a stain ? In both cases how can it be removed ? Thanks in advance