Liza,
Just wanted to mention, Maggie has been complaining of nausea as well last couple days, coincidentally she just started day camp. The days are warmer, she may not be eating as much at camp. Even though I send her with plenty of drinks and gatorade, she is having too much fun to sit and eat and drink. When she gets home, she drinks and drinks, I couldn't believe how much. I even woke her up so she wouldn't pee her bed from all the drinking. And she still woke up peed early, too. Then before camp downed 2 cups juice and about one cup of chocolate milk, YUK. I'm going to have her take it easy after camp today... I do think she is affected by the heat. And that is paritally accounting for some nausea. Hope your little guy is keeping cool!