Carprofen, veterinarian’s behavior-need advice

[ErinD2021]

I took my dog to a new vet and I’m a bit perturbed. My dog weighs 8 pounds a little mixed terrier breed, she’s 9 years old. She’s always acted like a puppy until a few weeks ago, just lost that bouncy, happy going 99 miles a hour playing, can do a 5 mile hike vibe.
The vet did a senior check and said everything looked good, some sort of tiny elevation in liver.
She had been acting like a much older dog recently which is why I took her in.
He said she seemed to have a little painful spot along her spine but again couldn’t detect anything major.
He handed me a bottle of carprofen 25 and said give as needed. No explanations of drug or warnings about side effects. I googled and am a bit upset about the casual way he gave a potentially dangerous drug for me to use! What is anyone’s opinion on this drug and the way the vet was about it??