Honestly, I think you should go to the vet and get antibiotics. Penny was only coughing "infrequently". Mostly at night. My vet said it sounds like KC because they seem to cough more at night. Something about them laying down. Which made sense to me, because, when she was in her bed there is an edge that she lays her head on, and she didn't cough as much as when she was laying flat. Penny's was caught early. They said if any more symptoms show, call them immediately. Hard coughing, green discharge from nose,not eating, runny stools. She is getting her meds twice a day. But they said even as it clears up the cough stays for as long as 6-8 weks. Except for the cough, she has no other symptoms-so far.(thank God)
This is just my opinion. Trying to help. sorry it is so long.