stomach issues?

my dog is always licking his lips and swallowing before and after eating and in his sleep.  it is very loud and very annoying. Also, after he eats he either vomits or burps and it smells PUTRID - like rotting meat or feces.  We recently changed his food but he was doing this before that too.  Our normal vet didn't have any answers as to what may cause it.  can it have something to do with digestion?  like maybe he feels he has to swallow for some reason? and how do we get rid of that awful smell?  It's not just his teeth.  he burped last night and it stunk up the whole living room.

[Aleda M Cheng, D.V.M., C.V.A]

There are quite a few possibilities for what may be wrong with your dog as follows:

Inflammatory Bowel Disease, Gastrointestinal parasites, Food Allergies, Pancreatic Insufficiency, partial blockage with a foreign body, gastric or duodenal ulcer and more.

It might be a good idea to have your dog treated for possible gastrointestinal parasites (even if a fecal analysis is negative).  I would also recommend  that you give probiotics, digestive enzymes (Prozyme or Wobenzym), and a hypoallergenic diet for starters.  The hypoallergenic diet must be a novel protein diet (something he has never been exposed to before).

If there is a possibility that your dog could have ingested a non-food item, which could have caused a partial blockage, or could have caused a perforation to his digestive tract, than you must have abdominal X-Rays, a barium study or an abdominal ultrasound.