Awwww, Poor Guy! Thats a toughie for sure!! But kisses and belly rubs from mom are a sure fire cure!!!
Of course you could always teach him the "Secret Tummy Ache Trick" I taught it to Katie. oops, Kate, when she was in the first grade... It got her perfect attendance the next two years!
When you feel icky Pinch your pinky fingertip, the whole thing nail and all, on your left hand.. with your right hand... and count to ten in your head s l o w l y. . . .

And then tell your self that its only a couple of hours till you get to come home!
Kate used it alot! lol and it worked! lol She never came home in the 1st or 2nd grade and only came home in the 3rd cause she was hurt on the playground... That she could not talk herself through... She said she tried! Poor baby!
Keep us posted and let us know how day 2 goes!