When my daughter was solely breast fed she, too, would go 4 or 5 days with no bowel movements and then have one and 4 more days. She did this for quite a while. I called her doctor and they said as long as she is solely breast fed and the bowel movements that she had weren't hard and hard to get out and that she was urinating, then this was very normal. Breast milk is the very best thing for your baby. It's made so perfectly that often it is completely used up and there is nothing to expell. This has happened to many of my friends' babies too who were solely breast fed! I just warned my neighbor about the possiblity of this happening and not to be worried because all I had ever read was to expect multiple bowel movements a day! Your baby is getting bigger now and getting close to the age when solids will be introduced. Maybe your baby is just using up all the milk? I hope all goes well. When my daughter was eating solids and didn't poop for a day or two, then I would grind a prune in the baby food grinder, not too much or you'll get diarrhea! (They're so little!) She LOVES prunes! I hope all goes well!