My 4 month old previously would have 5+ bms a day and this week this has been dramatically decreased to one or less a day. When should I call the dr?

See Below. As long as the bowel movements are normal, there is nothing to worry about. As children get older, the frequency of their bowel movements will decrease.
Depends. Breast fed babies can go a smudge every feed or one cradle filler once a week.Bottle babies usually go 2-3 times a day. Kids often change their pattern if you change their feed, like adding cereal (slows it ).As long as the stools are soft there is no reason to freak out.