My son has been in the hospital 4 times with the croup, the first time was really severe, he couldn't breathe at all, his chest caved it, I'm pretty sure the doctor freaked out. It was terrible. He's 16 months. As I type this I'm listening to the baby moniter as he is wheezing again! He has had guaifenesin (cough medicine/congestion, given once daily), had a breathing treatment before bed, and zyrtec, he also has a humidifier in his room. This happens all of the time. My husband and I both work full time and I get so upset because I can't stay home with my baby some days when I feel like I need to.... it's hard.
So any way... the only diagnosis I have recieved is reactive airway disease, which from what I gather is a way of saying... this could be something diagnosable, but as of now.. this is what we're going with. I wish we had more of an answer. When we go to the hospital and he has the croupy cough I always ask what can we do to prevent this.. and they have told me that there is nothing we can do other than what we are already doing to prevent it, it just happens I suppose.
With my son though the majority of the times it happens is when there is a change in the weather (which in southeast Louisiana, this happens every day) and it worsens when we go outside. I put him in the truck with windows down a little or take him outside to play (because he loves being outside more than anything and gets frustrated if we can't go out) and he coughs continuously.
My son's doctor gives him an antiobiotic shot and steriods every time he is sick as well as the normal breathing treatments 3 times a day (this is a mixture of albuterol and ipatropium, sometimes xopenex). He asks us to come back every two days until it clears up. I'm not sure what to do but I hope he grows out of it! Otherwise I hope we can get a diagnosis =/
I know this isn't helpful, but it's my experience. I haven't yet been able to really find an answer through my searching, but I'm hoping I can find out something soon.