My new adopted German Shorthair came down with what looked like kennel cough a day after coming with me. It went from initial sneezing to cough, to coughing up flem every 15 mins... He never threw up his food, just the junk sitting in his throat.
I started treating him with 1 teaspoon of honey and when he coughed I gently patted his chest to try and loosen some of the junk... It also gave the young dog some comfort to be held while coughing. Results were seen in 4-8 hrs. Now, he just has sniffles and occasional dry cough, which I will retreat with honey/lemon mix. Seems like it works.