I have a 1 yr old male neutered cat, vaccines are all up to date. About 1 week ago he started sounding hoarse, he had started sneaking out at night and hanging with his buddies, then yesterday he developed a wet sounding purr, then last night he started coughing, he seems to feel OK, he is still cleaning himself and is eating and drinking, he don't seem to be playing with our dog as much though. Please advise

Please take him to the vet who can check in his mouth and throat. We can't diagnose over the Internet and have no clue what could be wrong with him. He might have eaten something he shouldn't have or been bitten by something. We don't know.