I hope he's OK, now!

We had a similar experience earlier this fall. After Annika's first day of school she came home out of sorts and uncharacteristically whiney and clingy. (Having not been sick since we left SF in March, she didn't remember the word "sick", but even if she had she might not have associated it to stomach-related distress which was a new one for all of us.) I got the brunt of the attack(s), unfortunately. Poor kid. She felt ill, but I think the mechanics of throwing up scared her even more. It's hard to be a toddler.