My dog keeps licking the air and swallowing

Why Is My Dog Swallowing Continuously & Licking? - Cuteness
If your dog is constantly lickingandswallowing, odds are she's feeling nauseous. As PetHelpful explains, nausea causes drooling in dogs, and the swallowing occurs because she's trying to eliminate all that saliva in her mouth. Some dogs with nausea start licking odd objects, such as the walls.

Why Is My Dog Licking the Air? -
Lickingtheair is often a compulsive behavior that helps dogs cope with anxiety, but it can also be a sign that a dog isn't feeling well. In either case, it is not a behavior that should be ignored. According to the ASPCA, anxious dogs might use several different compulsive behaviors to soothe themselves.

My dog keeps stretching his neck
Mydog is constantly swallowing and licking lips in between. I think a big part of the problem is people are trying to compare dog behavior to cat behavior.