Yep, we've got that nasty kennel cough in my house too. Lily's had it for right at a month now, and we're still working on getting rid of it. NO FUN.
Hang in there. From what I've read, it just takes a while to clear up and in babies (like mine and yours both!!) I think it might even be a little longer. We're on round 2 of antibiotics now. Yuck! I've also done the humidifier as well.