Have you ever explored the idea that he is lactose intolerant? My child has been on soy since he was about 10 months old because i knew what the problem was right away because I had been diagnosed at 8 with lactose intolerance because of constant diarrhea! When we took away the milk in both cases no more diarrhea! Then later I had a second child she did not react to milk as sensitive as my son and I do an I still as an adult have the problem. When I was pregnant for the first time, I was on WIC, which gave me vouchers an directions to drink 8 glasses of milk a day! I said I dont think that is a good idea I havent drank that much milk since i was 8! And explained my diagnosis! Well they encouraged me to take the vouchers an drink reg milk so I did an by Sun, which mon prior was when i got the vouchers, so abt a week, my stomach was rollin an within 15 min i had to rush to the bathroom, plz excuse the next phrase, it was like Niagra Falls! Oh my goodness It was so bad that I thought I was gonna go into labor! Needless to say I didnt drink anymore milk and went and got my vouchers changed to lactose free milk! Now back to my daughter, the one who is less sensitive, but still affected differently! My children were at a state daycare! The state required so much milk per day! Well that ended up being for every meal an snack! I had already bought soy for my son an got a DR's note for him but was not concerned that it would effect my daughter but we had not had milk in the concentration that they had it in, whole milk and that many times a day! By the evening of the third day my daughter was so constipated she was screaming to poop and bled from her rectum because it was so hard! It took her 2-3 hard poops and bleeding before 3 days of hard bleeding poop got out of her system! So the very next day I went and got her some soy milk and a DR's note! And it just so hapoen that I shared my issue with "grandma like" door greeter at walmart and she too has had the constipation issue with lactose intolerance! Well then later when I spoke with the DR. she said although it is not as common as diarrhea, constipation is also a side effect of lactose intolerance! Another case I ran into with a family that used whole milk several times through the night to get a toddler to sleep plus gave him whole milk through out the day! He woke up every morning with hot diarrhea scalding him from back to front, he literally was blistered and bleeding! I cured him w a butt paste called triple paste from Sum Labs that i had found! And begged the parents t find another alternative! And shared my experience with them of Lactose Intolerance! Please dont let the state fool you there is other ways to get calcium! Oh and even if teeth are the problem I would switch to soy anyway just to be safe side! If Lactose Intolerance has not been discussed with his Pediatrician, I highly suggest it! Thanks for reading! W. from IN