This exact thing happened to June at this exact age too. We'd had her about 2 weeks (so she was 10 weeks old) and she would cough at night. She'd be fine during the day so we kept thinking she was fine, of course until night time when she would have the cough attacks again. She would just cough and then lay down wherever she was. Took her into the vet first thing on a Monday morning and she had no temp, and the vet said it was just a cough. She told me to give her some benedryl and gave us a cough suppressant that we cut in half for her. It was like over the counter Robitussin to give every 4-6 hours as necessary. Well it didn't get much better, and sounded a little worse even so Wednesday evening my bf and I decided to take her to the ER vet. It was after hours at our vet and we wanted a different opinion. Well $250 and x-rays later... same diagnosis- just a cough. We are first time dog owners and i'd read so much online about them getting pneumonia, so I jumped the gun on doing the x rays. She still had no fever and her lungs looked fine. The ER vet said it was just an upper respiratory infection and would just take time. She also didn't want to prescribe meds for such a young puppy because that could do more harm than good. Go figure the next day she was totally fine!! So all in all it was about a week of the coughing. We just made sure she had plenty of water, and even put warm water in her food to help (we still do this now). Hopefully the same goes for Ace