There's some black stuff I the umbilical region for my little kid who is 4 months old now. Is there anything to worry about it?

A. Dip a cotton swab in rubbing alcohol and gently rub the surfaces inside your bellybutton. If the swab gets dirty, throw it away and start a new one. Once the cotton swab comes out clean, use a fresh one dipped in water to rinse the alcohol out of your bellybutton so it doesn't dry your skin.