Kiddin' Me?!?!?!

So, almost first thing this morning, a relatively cheerful, fully dressed Isaac informed me that his stomach hurt.  He went and laid down in the bathroom.  Wanted to drink water, so guzzled a bunch of that.  Then I got to thinking - he hardly ate anything at supper last night, and when he does that, often he feels sick.  So, I got him some breakfast.  Said he burped and felt like he was going to throw up and didn't think he could eat the Cheerios and banana I had for him, so I got him applesauce.  He picked at it, but hardly ate any.  To make matters stranger, he was joking and talking and stuff as usual.  An hour after he told me his stomach hurt, he threw up.  Now he's back on the bathroom floor, but for a while, he was yelling to his sisters in the other room and said he felt good.  Said he even felt good when he threw up.  (Enter Pause here as I went back to be with Isaac as he threw up AGAIN.)  What in tarnation is going on?!?!?!  Poor fella.  Thankful everyone stayed well last night so we got some sleep....