Hello, I'm Dr. Kara. I have over 20 years of experience as a veterinarian and I'd like to help with your concerns about Lulu's vomiting and loss of appetite while she is on Atopica and Rimadyl.
If she were to have nausea from Atopica I would have expected her to be nauseous in the first week or two of it being given. I would not expect her to suddenly get nauseous 6 weeks after starting Atopica. Most of the time we can get them past this nausea by giving the medication at a half dose for the first couple of weeks and giving the medication with food.
If her nausea began after starting Rimadyl then I would be inclined to believe that Rimadyl is either the primary problem or at least playing a part in her nausea. For now you may want to discontinue Rimadyl until we know.
Or given that both drugs are metabolized by the liver perhaps her liver is being damaged by using both medications together.
At this point I would recommend having her examined by her veterinarian and checking some blood tests to make sure her internal organ function has not been affected.
In the meantime at home to settle her stomach you can give either:
1) Pepcid ac (famotidine) at ¼ of a 10mg tablet per 5 to 10 pounds of body weight every 12 hours
2) Prilosec (omeprazole) at ¼ of a 10mg tablet per 5 to 10 pounds of body weight every 24 hours
These are acid reducers and may help settle her stomach and get her to her feel better.
You can also feed a homemade bland diet consisting of 1/3 boiled hamburger or white, skinless chicken, all fats and juices drained and 2/3 white rice. Add low salt beef or chicken broth to increase fluid intake which should help her feel better.
Best of luck with your girl, please let me know if you have any further questions.