... so I stayed home from work to watch him. He was fine yesterday but he only had Gatorade to drink. This morning I gave him milk and he threw up in the car on the way to school. I'm not very smart but I used my puny powers of deduction and came up with a conclusion. It's the milk.
Or more precisely, the Lactaid. It was a new carton, but it smelled slightly sour so I dumped it out. I will give him some more milk this afternoon and see how he does. I'm hoping it was only a bad carton. He is acting fine. He is cheerful and playing with his toys. Maybe he just wanted to hang out with me today.