I have a 5 year old boy that had a similar problem at age 1 but was never diagnosed. My son had already learned how to bring up mucus from his throat and chest. There is a Homeopathic Expectorant Cough Syrup approved for any age where a child can clear their throat.
This Cough Syrup has been around for 20 years and rarely ever fails children or adults. It has immune stabilizing ingredients and mucus dissolving properties.
The best way to use it for that age would be ¼ tsp. 4 to 6 times a day in the mouth. Keep this on mind if she does not improve very soon. This type of condition needs to be resolved in 7 to 10 days or can lead to asthma later on in life from the inflammation scarring the bronchioles.
You can research the product at:
Kim (using my husbands sign-in)