Suggest Treatment For Cough, Headaches And Chest Pain

My 13 year old has had a cough for seven weeks, she has had two courses of antibiotic, one week of 30mg prednisone and a venturing inhaler. She has now finished these medications. She does not have a temperature, she now has headaches, cough, green phlegm pain in chest, upset stomach and is sleeping during the day, our gp told her there is nothing else she can take. Any suggestions.