I had a similar experience with my twins recently. I feed them raw milk, which they love and thrive on. But right around the holidays, the main dairy that produces it in California was quarantined for a E coli scare (turned out not to be from them) and the supply dried up. So we tried giving them pasteurized organic milk. What a mistake! They pooped constantly and would instantly get painful, red diaper rash. They were screaming in pain. It was horrible.
I committed to finding raw milk for them come hell or high water. There was one other producer up in Northern California, who was obviously overwhelmed, and rationing out milk to their dealers (of which there were few in So Cal). So I'd stalk the delivery van, call stores for delivery times, stand in line after line for hours at a time to get two quarts of raw milk (at $8.00 a quart!) and I kept doing that for weeks until the quarantine was lifted on my regular dairy. What a nightmare. But as soon as we went back to raw milk, all the problems went away.
Factory food is crap. The two remaining dairies in California that produce raw milk are under constant assault from the mainstream dairy industry and the government. Neither will be happy until raw milk is banned for good, like it is in many other States. And then even more people, including children, will suffer. It's amazing what the "experts" and "authorities" want us to believe is wholesome food. Disgusting.