Is this normal?

Gerycah

She is almost 3 weeks old( she will be 3 weeks tomorrow) she lost her umbilical cord a week after birth and everything was healing fine, went to her one we check up and dr said it was healing perfectly. But today during a diaper change it looked like this, when a few hours before hand it was perfectly fine. Should I call her Dr? Or just clean it? If so how do I clean it?