What does a person feel like the day after being hit hard in the stomach?

Yesterday evening, my son crashed on his bike and whacked himself hard in the belly with the handlebars on the way down. He knocked the air right out of himself, poor guy, but after a few gasps (and a bit of puking) said he felt better. I checked with the doctor about signs to watch for because I keep thinking of internal bleeding. Nothing of concern, and he slept well last night and is in good spirits.

However, he says he has a stomach ache. It hurts when he stands up straight or laughs. He’s not crying, and other than complaining and saying he can’t go to school, he’s acting normal. He’s 7, by the way. To make me even more conflicted, he was complaining of a stomach ache yesterday afternoon and during dinner, before he got hurt.

For those of you who have taken a good blow to the stomach, is soreness the next day typical? How long did it last?