I think that taking Buttons to the vet is the right move. Could be nothing...a cold...allergies...
I know that in my state, kennel cough is not required, just recommended. What are the laws in yours? Has she been around other dogs besides your own? Or have yours been around others besides her? I would only worry about kennel cough if they have. Otherwise, it's unusual from what I understand. Could be allergies to the chemicals in the carpet. How are the others doing?
You are very brave, getting a new carpet and a puppy at the same time!