Infectious Tracheobronchitis (Kennel Cough)
here is info on kennel cough - the runny nose and sneezing could be signs of both kennel cough or reverse sneeze does your dog have allergies? the videos for all three are below so maybe that will help you
also take a video of it on your video camera and post and take into vet so he can see what is happening as they never do it in the office