Hello,
Wow, tough call.
It very well could be either.
Easily, a reaction to vaccines is suspected. However, Deramaxx, as well as many of the other non-steroidal anti-inflammatory drugs, can induce stop vomiting and nausea as well.
Either way, WELL WORTH getting into a vet today for supportive care, especially if a vaccine reaction.
To help settle the stomach you could try one of the following drugs. My favorite product is Pepcid (an over-the-counter antacid).
Pepcid (Pepcid A.C.)
Pepcid comes in 10mg or 20mg tablets. You can give it every 12 hours.
The dose can be found within the following link:
http://www.petplace.com/drug-library/famotidine-pepcid/page1.aspx
Prilosec
http://www.petplace.com/drug-library/omeprazole-prilosec/page1.aspx
Zantac (Ranitidine)
http://www.petplace.com/drug-library/ranitidine-hcl-zantac/page1.aspx
Any of the above should NOT replace getting into a vet today.
Good Luck
Dr. Andy
Veterinarian
UC Davis grad, Interests: Internal Medicine, Dermatology, Pain Control, Emergency