The reason a belly button is leaking fluid may be due an infection, according to MedGuidance.com. The most common sources of infection are piercings, yeast or fungal infections and obesity.
Bacteria growth resulting in belly button infections can cause discharge and odor. These infections can be initiated by bacteria or fungus or may be a side effect of previous surgery, diabetes, an urachus tube opening or cysts. Depending on the cause of the discharge, these issues can be treated by surgery, a change in diet and hygiene or topical treatments. Keep the belly button clean and dry and seek medical attention to address any pain, smell or discharge coming from the belly button.