Is your son acting ready for oral food? and is the formula or breast milk holding him or does he continue to act "hungry"? that is when you feed food. not when the doctor says. it is amazing in the old days that when there were not doctors around to tell people when to start a baby on food, they still managed to do it.
you don't need your doctors permission to give your baby food, pro-biotics, or yogurt.
yes, there are studies that point to delaying giving milk products to children with a family history of asthma until after one year old, yes there are studies about food allergies and babies etc. but they are just guidelines.
basically, when the baby is ready for food he will tell you. you will know.
all mine were breast fed, and they all started on cereal at 3 months. they were all 9lb babies and were starving. my third one nursed every 2 hours for 45 minutes, that left an hour and fifteen minutes to do other things like sleep, or deal with my two other sons, 5 and 3. and he did that for 6 weeks. until i supplemented him with formula. and my milk gushed like a cow and was thick and creamy. he was just hungry.
the second thing i started my babies on was yogurt in with the cereal to give them some protein to hold them over. it takes longer to digest the protein then the carbs from the cereal, so therefore they stayed fuller longer. it was the best thing i ever did. they are extremely healthy kids. seldom even get sick, like colds etc., as babies or now. and i attribute it to getting lots of good healthy bacteria at a young age.
I would start the baby off with yogurt if he develops diarrhea. you can get a low sugar kind, you can get organic from the health food store, there are alot of choices. make sure there are as few ingredients as possible, no chunks of fruit and that it has active cultures. you can also buy straight cultures at the health food store and add to a bottle. or you can get any number of probiotics to add to his bottle or food when you start him on food. the probiotics are bacteria, so a good number of them will be killed off by the antibiotics anyway. mainly you are giving them to re-inoculate the gut with the good bacteria killed off by the antibiotics, so the bad bacteria that are not susceptible to the antibiotic do not overgrow and cause diarrhea. basically, it is a system of checks and balances in the gut. and the antibiotics throw off the balance. the yogurt or other pro-biotics will also help prevent a secondary yeast infrection also. and help maintain the balance in the gut.
L.