Singulair/advair

my son was recently dx w/asthma after an er vis that led to a hosp due to this condition. he's 12yrs old. he was fine for 1 mon after hosp and symptons started w/cough and drop in peek flow. main symptom is cough lasting 4 wks now. he gets coughing spells thoughout the day that cause him to gag & sometimes vomit(spells are becoming less) he's been to dr many times in the past month,finally dr referred him to allergist.(goes soon)he's been taking advair and zyrtec-dr took him off of zrytec as poss coughing spells. just put him on singulair along w/advair. I'm hoping/praying that it works! nothing more terrible for a parent to see there child suffer like this and nobody really know whats going on! 1st drs thought asthma flare up thats lasting long time w/cold now poss allergies!! very frustrated mom feeling helpless! has anybody had a cough as main symptom w/asthma and found out it's due to allergies? need some encouragement and hope!!!