Hello I am Dr. Joey. Thanks for trusting me to help you and your pet today. I am a licensed veterinarian with over 16 years of experience. I look forward to working with you.
This certainly is concerning to have lasted a week. Any toxicity related to ingestion of chocolate is highly unlikely as this would have occurred within the first 24 hours. That means my top worry is she may have developed pancreatitis secondary to the ingestion, which is going to require some therapy. Or, the vomiting may be unrelated to the cupcake ingestion.
It sounds like she has not been seen by her veterinarian, and it is now time to have her examined. She needs this exam and some lab testing that might include a complete blood count, chemistry profile with electrolytes an during check +/- stool check. This will screen for pancreatitis, organ problems (liver, kidney, etc), infection issues. And a stool sample to be looked at for bacteria, in particular, will help us to know if she is having a shift in the normal population. If there is concern she might have swallowed something other than the cupcakes which may be in her stomach, then radiographs (X-rays) are indicated to screen for this.
Without doing further testing I am not sure we can provide an exact diagnosis for her issues. In addition to a bland diet at home (chicken and white rice), the only safe over-the-counter anti nausea medication that you can get is famotidine (Pepcid AD) and she could take a tab every 12 hours. This helps with sour stomach but is not a potent anti-vomiting medication. Your veterinarian would have to prescribe something stronger to help stop the vomiting and aid in settling her system.
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