Hello, my name is***** and I have over 20 years of experience as a veterinarian. I'm sorry to hear that Harvey is sneezing and snorting, and running a fever and I understand that you are concerned about him.
A sneeze simply means he is experiencing airway irritation. A sneeze can be related to a viral, bacterial, fungal or parasitic infection.
In a young dog infectious disease is by far the most common cause. Of those kennel cough or infectious tracheobronchitis is one of the most common causes.
Because he has recently been to a boarding kennel, kennel cough would be high on my list of possible problems. I understand that he has been vaccinated but we cannot vaccinate against all of the agents that cause kennel cough and some dogs will still get sick even with the vaccine. The good news is that dogs that are vaccinated usually don't get as sick as dogs that haven't been vaccinated.
As long as he is still eating and drinking well, isn't lethargic, isn't running a fever (rectal temperature greater then 39.4C), and he doesn't have a green or yellow nasal or eye discharge then you can try taking a watch and see approach.
Make sure he gets plenty of fluids, lots of rest as the more active he is then more he will sneeze and snort and may start to cough. And make sure he eats well. It may help to add warm water or broth to his food to make it more enticing and get additional fluids un as well as making it softer and more comfortable for a sore throat.
You can take him into the bathroom with you when you take a hot bath or shower so he can breathe the steam which is soothing to his airways, and will thin mucous making it easier to breathe.
His symptoms should slowly resolve over the nest 2 to 3 weeks.
There are other respiratory infections he could have picked up, but kennel cough seems most likely with his history.
If his symptoms are lingering or he becomes very lethargic, he runs a fever, or his appetite is poor then he should see his veterinarian for an examination and some testing.
Best of luck with Harvey, please let me know if you have any further questions.