Thanks so much, everyone, for sharing your experiences and for all of your great advice. Luckily he's back to his sweet self... for now anyway. I'm glad to hear how common this behavior is. Hopefully it won't happen again for a long time (I know, wishful thinking!), but the next time it does, at least I'll have some idea how to handle it.

My boy has now moved on from tantrums to manipulative charming behavior. I've been home for a few weeks now, so grandma doesn't give him what he wants all the time anymore and he realizes that tantrums don't work. So now he comes around with a big smile, tells me "mommy, I wuv you," followed by hugs and lots of kisses. Then he asks for his cookie again (or whatever it is he wants, like going for a walk yesterday, in the middle of a thunderstorm). And he's not even 2!!! How did he figure it out?!?

Sounds adorable, Einstein! I can't wait until my little guy can say, "Mommy, I wuv you!" too.