Karsyn is almost 3 weeks old belly button cord hasnt fallen off yet it has an odor and green underneath ive taken him to…

Karsyn is almost 3 weeks old belly button cord hasnt fallen off yet it has an odor and green underneath ive taken him to pediatrician who says unless it's red swollen or streaks its not a cause for concern. However none of my other kids I remember had this problem. Just wondering if any one else has experienced this and all was normal?