Is the stool hard when he finally goes? My daughter used to go a few days before pooping then have a huge blow out. It wasn't until we started solids that she had REAL constipation. Where the stool was dry and hard and painful to pass. For her, Bananas are extremely binding! Another poster mention acidophilous (sp), my Ped recommended this as well for my daughter, as her constipation was pretty severe. Don't give up breastfeeding though, its still the best thing you can do for your baby!
Found this for you
Constipation in the Breastfed Baby
By Mary Bibb, BA, IBCLC
Breastfed newborn babies younger than 6 weeks old should have at least 3 stools a day. A young baby who is not stooling often probably needs more milk. An IBCLC can help with concerns about milk supply and baby’s milk intake. Having fewer than 3-5 bowel movements a day is not a problem if the baby is gaining weight well.
After 6 weeks of age, some healthy breastfed babies have bowel movements far less often. If the baby seems happy, is gaining weight well, and the stools are soft when they are passed, then it is not a problem. Usually the stool will be very large if it has been a few days (or even more) since baby last made a dirty diaper.
Constipation occurs when the stool is hard and dry when it is passed, not when baby has infrequent stools. A constipated baby might be ill, especially if he is also vomiting frequently, does not want to breastfeed, seems weak and has a dry mouth. If your baby has these symptoms, get immediate medical care.
Babies and toddlers can get constipated from cow’s milk based formulas, cow’s milk and rice cereal. Exclusively breastfed babies rarely get constipated, but once other foods are added the stools get firmer. The baby’s doctor, a registered dietician, or an IBCLC can help you figure out which foods might be causing a problem. Check with the baby’s doctor if you are concerned about your baby’s pattern of bowel movements.