I am so sorry your boy is not feeling well.
Dogs get upper respiratory infections, kennel cough and canine influenza Some are so contagious, they can come in on shoes. I will try to cover every possibility.
It can also be kennel cough, a reverse sneeze, an allergy or swallowed non food item.
Excitation does worsen this condition.
Kennel cough will usually resolve on it's own in about three weeks. Sometimes vets do script antibiotics to prevent secondary infections. Doxycyline is the most common one used.
You can also use robitussin to give him relief.
Here is info on Kennel cough:
His throat my be scratchy I would pick up any dog food.Try a small amount of boiled chicken with all fat drained off, cottage cheese, baby food with no onion, beef, turkey, etc
Add unflavored pedialyte to his water 50/50 to hydrate him and balance his electrolytes.
Put a drop of pancake syrup on his tongue to raise his blood sugar in case he is a bit hypoglycemic. Do not allow him to drink a lot at a time If he throws up water, he can lick ice
She may have any human OTC at www.wolfdancer.org/health scroll down for products and dosages.
Keep him on that very light diet of boiled chicken or cottage cheese for 48 hours. Also give him one teaspoon a day of plain yogurt to keep "good" bacteria in his system.
He should see the vet if he gets worse or developes any breathing difficulties.
I hope I have covered every possibility. Please let know if you still have questions and how your baby is doing, I will always be here for both of you.
I hope he feels better very soon.