Coughing, Runny nouse after 2 months?

[meyo]

My 18 months old son start coughing, after a cold in mid may 2007, after 2 or 3 week of no improvements (no fever or lack of appetite), his ped diagnosed bronchitis and prescribed Azytromycin (for 3 days), Xopenex every 4 hours until cough succeed and suggested an X-ray. The next day the X-ray showed a possible pneumonia, so he was put on Omnicef too for 10 days. A new X-ray showed "noticeable improvements"
Two days after he finished Omnicef he develops a mild fever, so he was put on Septra for 10 days, and continuing his breathing treatment with Xopenex once a day. The fever succeed but no the cough. The doctors kept saying his lungs sound clear...
We went to a Allergy & Asthma specialist, my son  allergy test was positive for Johnson grass, Mold and Cat dander (we don't have pets), and the doctor suggested us that my son maybe never had pneumonia that what he had was an asthma attack. He then was put on Pulmicort twice a day. Xopenex every 4 hours as needed and Singular, he slightly improved the following week, and then we stopped Xopenex ...He starts with a runny noose, and coughing again!!! This is just bad luck and he caught up a cold, or is the pneumonia after effects, or is any chance that he is really asthmatic?? what's going on??? and What is next???

Please help!