See doctor... Possibilities include bronchospasm from any etiology, including a possible reaction to the cough medicine itself. If she is experiencing shortness of breath, or if her symptoms are worsening, see a doctor urgently, including er. Other possible etiologies for the cough include bronchitis, gerd, sinus problems or even a combination of factors. Good luck!
GET SEEN, inc. cough. A cough that seems to be worsening should be checked for pneumonia. Other signs may include chest pain with breathing, fatigue, phlegm production, fever, chills, sweats. A chest xray may be taken and pulse ox (oxygen level) will be checked. Whooping cough is prevalent everywhere and washington state has had 1800 cases so far in 2012!