The fungus candida thrives in dark, warm, moist places like your belly button. It causes a rash of dry, itchy, swollen skin. You’re more likely to get it if you’re pregnant, obese, or take antibiotics. You can help prevent it if you wear looser clothing and keep your navel clean, especially in hot, humid weather. You treat it with antifungal creams, powders, or lotions rubbed directly on the area.