Well, actually it's more like Katie and Julie have run into a bug -- more digestive in Julie's case -- that has laid them moderately low. This involves running around like crazy until the energy runs out, then collapsing in a heap, then running around. That's pretty much normal, I suppose, except for the frequency of collapsing in a heap and the duration of the collapse. And the digestive distress.
We've tried to get Katie to take the children's ibuprofen, but she's adamantly refusing because it "tastes yucky". *sigh* And no amount of persuasion has worked thus far.
They're off to bed relatively early. Here's hoping they feel better tomorrow.