Sick...Again?

Today started off good and as far as I could tell Trevor felt fine. We played inside and outside then came back in this afternoon and Trevor ended up falling asleep on the couch at about 4, right after he told me his tummy hurt. When he woke up he acted okay, then just threw up a ton.
This is him after his bath.
He didn't have any kind of fever at all, so I don't know what is going on. He said he felt better and acted like it for the rest of the evening up until about 20 minutes before bed. I sent him to bed with a dose of Motrin, just in case, and a bowl by his bed.