Umbilical cord question???

MaKayla • 💕Vet Tech graduate🐶FTM to Ash💕

I’m a FTM and my sons umbilical cord seems to be slowly coming off but there is some yellow pocket underneath?? He is 12 days old and it just happened today? He has an appointment on Thursday. Should I be concerned or is it normal?? Should I try to see the pediatrician sooner?