Kennel cough can sound pretty awful. My little guy had it. he sounded like an 80 year old smoker hacking away.
Ask your vet for some Doxycycline. Usually a 2 week cycle of antibiotics will clear it up. Going to the vet is a must though. Since there are 2 dogs around, I would suggest having them both checked out so the illness doesn't keep coming back.
Best of luck
As for where he caught it from could be anywhere but the vets office could do it. I know most offices are pretty strict, if they know of a case coming in they try to keep them separate but still what if the person doesnt know? Last time my hubby took the boys to the vet someone came in and was asked to go back outside and fast, turned out that pup had it.
Yes..like @cal-jenn said..you can get from vets or anywhere an infected dog has been! Did he have a bordatello shot? My daughters dog got it even though he was vaccinated! Poor guy..it's nasty! Hope he feels better.