Kirsten, I'm so sorry to hear about poor Luna. Yes, it does sound like the medicine may be causing her tummy to become upset. When my cats get their teeth cleaned, my vet recommends that they take some antibiotics for a week. Well Sunny was also having problems and began throwing up. He's been on this same antibiotic before without any problems but for some reason his stomach couldn't handle it this time. I called too late on Sat. because the vet was already gone. They told me to try giving him 1/2 the amount 2 times a day. I tried this and he still threw up. On Mon. morning the vet told me to just stop the antibiotics.

Hopefully Luna will feel better soon. She may have to take another kind of antibiotic. I'd also try calling an emergency clinic to ask for advice. Good luck.