singulair is more mild than ventolin. Ventolin cannot be taken for a long time, the size effect is the hands will be shaking.
Why did your son need to take so many anti-biotic ? The immunse will not be so good after taking so many and it takes time to re-build and make it stronger. Did you ever bring your son to consult the Chinese doctor ?
When my girl cough, she has 痰 (I think), however, we have not let her take any cold drinks, sweet things, then I touch the vomit things and find it is very sticky just like some 分泌 substance. Afterwards, her cough will be changed to DRY咳. Sometimes, the whole process may be last for an hour or half an hour (depends).
However, recently, I keep on boiling the crocodile meat soup and sea horse soup. Touchwood, her cough is less than before. None on Saturday, 30 mins on Sunday, none on Monday.