My belly piercing has been red for a month is it ok ?

No, it's not. It's infected. Just because it doesn't look like it's spreading doesn't mean it isn't. It could be spreading internally. I've heard stories about people losing a section of their bowels from piecing infection, which means you could end up with a crap bag tied to your leg forever, if not dead.

GO TO A DOCTOR!!!!! And insist on antibiotics, because some doctors are stupid!!!!!!