Don't change the ring that you were originally pierced wtih. Dark colors are definately not a part of normal healing - I would reccomend that you go back to the place where you got it pierced and they can suggest an over the counter cleaning solution (like Mecca, that's what I used) or refer you to a doctor for an antibiotic perscription. In the mean time if you are feeling sore at all, take a shot glass, put 1/2 a tea spoon of epsom salts in it and fill to 3/4 with water... put the shot glass in the microwave for 40 seconds and then flip it upside down over your belly button.