My dog is a 8 year-old, Golden Retriever. He acts like he doesn't like the smell of his food bowl. He used to be food crazed dog. He would eat just about anything. Ever since I brought him for his grooming (2 weeks ago), he seems like he lost his appetite. He will not eat his dog food (dry). I thought he could be having some kind of dental problem so I started to give him can food which he seemed to enjoy. But now, his back leg seems to be shaking involuntarily and he didn't even finish his can food. Am I being too sensitive? What should I do?
He has lumps near his belly on his side as well. When I took him to the vet for the annual vaccines last year, the vet wasn't very concerend about it. He got a couple more since then. Ah~ I am so stressed out.

It's time for another vet visit, and maybe with a different vet. Eight years old is getting up there.

I agree with Wondergirl, sounds like a visit to the vet is in order.

The leg shaking could be him trying to scratch perhaps? That would tie in with the lumps on his stomach.
Any time you change a dogs diet you have to keep an eye out for allergic reactions. Some dogs are highly allergic to ingredients in dog foods, others just have a mild sensitivity. One of mine has problems with beef, it is just enough to make him itchy, but not show many signs.

Dental problems in an 8 year old are also a high possibility. How do his teeth look? Any tartar build up or gum redness?

Yes, he does have a lot of tartar build-ups. His tongue and paws are cold today and his nose is running. What do you think that is? I just spent $30 to ask a vet technician this question online. He doesn't look like he's in any pain.

I did make an appointment for Monday, next week. I hope he doesn't get worse.