sounds infected to me. maybe twice a day take out your bar and wash the hole really well with either an antibacterial solution or warm salty water. if you can not take you bar out, that's okay, but just make sure you continually move it around and get the cleaning solution right into the hole and try to flush out the infection. if it gets worse or you can seem to handle it, best get to the DR as you may need a course of antibiotics and you DR could say you need to permanently remove the bar. it would have gotten infected from not keeping it clean proplerly, so always wash well when you are in the shower right inside your belly button and everything
I actually like belly piercing with really complementary jewelry - I never thought I'd admit this until women I know have shown me truly artistic and semi-erotic piercings - well beyond the naval. My medical advice is simply this: see an MD - you probably want to see a dermatologist if your insurance allows direct specialist assessment. I know many women that have had the same or similar problems with all kinds of piercings - the fix will always be with scientifically trained experts - otherwise known as "doctors".