One of the dogs at my training class turned out to have kennel cough. I skipped a class in addition to the one she missed with her dog. Thanks to the advise of another person on this board, even though she had her shot, I had to curtail my dog's activities for several weeks. Fortunately she did not catch it, but I had to look out for other dogs just in case. Do not mix your dog with another dog, not even casually, please.
Please get to the vet pronto.