I have horrible asthma, allergy problems all my life and sound like your daughter;s problems. I also use a cool mist humidifer especially in the winter. Right now I'm having another allergy problem even with all the meds I'm on. Everynight almost, I rub some vick's on my nose to keep the passage way in my nose open.
I also have the same problem with milk especially during an out break. It makes me start coughing and hacking like no tomorrow. Also when she starts coughing and carrying on try giving her something warm to drink especially something like hot chocolate with a dash of coffee in it. It really does help or has helped me. The last thing I learned recently is that all those plug in smell good thingys are horrible for people with allergies because of the oils released get into the nasal cavity and can solidfy there. I learned this from my allergist/asthma doctor a few months ago.