It's rare that a healing umbilical cord stump gets infected, but it can happen. See a doctor if your newborn seems to be in pain or if you notice any of these signs of infection:
- Red, swollen appearance
- A fluid-filled lump on or near baby's umbilical-cord stump
- Oozing pus or any foul-smelling discharge
- Bleeding from the scab (a little dried blood is normal)
- Fever
- Lethargy, low appetite, irritability
- Abdominal swelling
If baby does have an infection, your doctor will prescribe antibiotics to clear it up.
http://www.whattoexpect.com/baby-growth/umbilical-cord-care.aspx