Although the lack of BMs in a 7 day old baby is surely a red flag, I have had at least 2 cases (in 12 years!) where a similar chain of events occured, but the baby was wetting a great deal and everything was fine. As long as:
1-the baby is nursing at least 10-12 times a day
2-the mother and baby are comfortable
3-the baby is weighed and is gaining weight
4-the baby is having lots of good wet diapers
I wouldn't be terribly concerned.
Barbara Leshin-Zucker, IBCLC
Highland Mills, NY