How do I know if it is RAD or just allergies?

At the age of two, my daughter was diagnosed with RAD after a bout of coughing and wheezing from a cold.  The doctor did a chest x-ray and tested her for Cystic Fibrosis and both came back negative.  They prescribed Flovent twice a day, every day.  I gave her the Flovent for over a year and gave her nebulizer treatments when she started to get sick.  After her nebulizer treatments she would cough violently for several hours.  I found that neither the Flovent nor the treatments helped her.  It is my opinion that she is coughing mostly at night and that is a result of post nasal drip.  When she lies down her sinuses completely close up and she starts to cough.  She breathes through her mouth all year round.  My doctors insist that I give her the nebulizer treatments when she is sick, but my intuition tells me that I shouldn't.  I was informed that if I don't, I could cause her permanent lung damage.  Yesterday, she started with a bad cough.  Myself and my 15 mth old just got over bronchitis, so I started her on the nebulizer treatments.  Her coughing became worse, not better.  Later in the day she broke out in hives over her entire body.  I gave her an antihistamine and her cough has almost stopped.  She is 4 1/2 now and has never had another bout of the wheezing.  She rarely coughs during exercise and is very active.  When she has a cold, her nose is rarely runny, but she does cough.  Should I see an allergist or a pulmonologist for alternative treatments?  Of course I want to do what is best for my child, but I just don't see how the nebulizer and Flovent treatments help.

[National Jewish]

Defining the cause of the cough should be the first priority. Your daughter has had this on and off for over a year, despite therapy. Seeing a specialist is a good first step toward this end. It is quite possible that this problem originates from the upper airway and is not being controlled by therapies for the lower airways.