Ds2 turned 1 a few weeks ago and we started introducing cow's milk as his main drink a few days before his birthday. This could be a coincidence but he seemed to get really grumpy and sensitive when he'd been on it a few days. I carried on with the cow's milk, thinking he was just under the weather, but when the grumpiness continued and his poos started to get much sloppier I put him back on formula (just normal cow's milk formula - SMA) and after about 2 days he seemed back to his usual self (though the poos didn't improve). I tried him on cow's milk again a couple of weeks later twice (one evening then the following morning) and the grumpiness returned big time. So back to formula.
So my question is: what kind of problem could he have with cow's milk, but not any other form of dairy, including cow's milk formula? The only info I can find on milk intolerances/allergies seems to include all dairy. He's had copious amounts of yogurt and cheese, and some formula milk, right from weaning and never had a problem with it.
TIA