That is good news! If he were seriously ill, his gums might look pale, and he might not be eating well.
This could be an upper respiratory infection, like "kennel cough
". If that is the case, he would need a course of antibiotics like doxycycline
If I could, I would listen to his heart and lungs, to be sure there was no heart murmur, and no sounds of fluids in his lungs. I would put pressure on his windpipe in the middle of his throat, give it a little squeeze, to see if that made him cough (if it does, this is probably an upper respiratory infection, or "tracheobronchitis"). I would feel his lymph nodes, and take his rectal temperature (normal is between 101 and 102).
If all that were normal, I would start a course of doxycycline, an antibiotic, and maybe a cough suppressant. You can get Robitussin DM
over the counter, and give him 1/4th to 1/2 of the adult dose on the label. Only get Robitussin DM, no other form.
If any of my exam was abnormal, I would take a chest Xray.
Let me know what other questions you have.