What Causes Pain In Belly Button?

I have a painful belly button. There is also a brownish discharge that takes about three hours to refill the cavity after cleaning it out. The discharge is extremely smelly and resembles a fecal odor. I also experience pain when the area around the belly button is palpated, primarily directly below. Two sores are now apparent in the cavity but were not there a week ago when the symptoms first appeared. The amount of discharge has been constant regardless of the presence of the sores. I do not have a fever. I've seen two doctors about this condition. One prescribed a topical cream called Mupirocin Ointment. The next prescribed an antibiotic pill called Sulfamethoxazole. Both have been ineffective at relieving any of the symptoms.