Mine is a bit younger, but I find that he nearly goes off food entirely when he's sick.

The truth is that as long as she's getting enough fluids, don't let it stress you out too much. I would try to stick to your eating routine/rules as much as possible, but if she's really miserable I wouldn't push it. You can readjust when she's feeling better. That's my strategy, anyhow.
I hope she gets better soon!