Thanks for the additional information. I really appreciate it.
You have every right to be concerned. Your dog is showing all the classic symptoms of an intestinal obstruction...the trembling (which is often a sign of pain), lethargy, anorexia and tight abdomen in the days after getting into the garbage are HUGE warning signs that your vet needs to be seen by a vet immediately.
An intestinal obstruction (likely caused by whatever else he ate out of the garbage) is what happens when the dog ingests something that is too big or too bulky to pass through the digestive tract the normal way. It gets stuck on one of the turns in the intestines and stops the flow of everything, causing your dog to get sicker and sicker until the intestine ruptures (if left untreated).
This is something that is absolutely, positively worth the drive to the emergency vet tonight. . Since your dog is already showing signs of obstruction I would strongly urge you to NOT wait until morning to have him seen...intestinal obstructions can turn fatal very quickly, so time is of the essence here.
If you're not sure where an emergency vet is in your area, you can go to: http://www.vetlocator.com and plug in your zip code. They'll point you in the direction of the one nearest to you.
At the emergency vet, they'll take an x-ray to see where the obstruction is and if it's still high up in the digestive tract, they'll have to remove it surgically.
You can read more about obstructions below:
I hope everything works out.