Lani
My son had a cough also a while back that lasted for a long time,after going to 4 doctors, the one at the childrens' hospital concluded that he had an upper respiratory infection, and that he was allergic to a cold virus he had contrated. He gave me inhalers to give him to clear out his lungs (combivient I believe). Also a holistic physician had told me about a candidas fungis... normally in the small intestines when diet is imbalanced this little fungis guy moves around the body and makes you sick. What I have done to prevent his asthma like colds...is I only give him Acidolphilus Milk, and have limited him on sugar intake. This seems to work very well. Good luck.