I'm not familiar with Cerenia (just googled it, though). But when my Odd Cat was on chemo, I was giving him Zofran. It was expensive (I paid about $300 for 9 pills), but it worked. My vet didn't stock it - they gave me a script & I went to the drugstore. I frequently give it at work to nauseated patients & it works like a charm.
Like Lynn said, just let her eat whatever she wants at this point, even if it's only milk bones or whatever, as long as she's keeping it down.