Hello You are having cough since 10 days and taking only cough syrup dextromethophan+guaiphensin, this is only a symptomatic relief provider. Since 10 days passed and cough is only in the nigh so may be due to decrease in temperature at night and some allergy and ifection . When such type of patient visit I advise my patient to take montelukast+ bambuterol tablet one at the night . Some patient feels mild fine tremors with this tablet so don t worry , the medicine adjust 2-3 days . Also take levofloxacin 10 mg / kg body weight once in day ( 750 mg will be sufficient)with pantaprazole ( so that patient don t feel dizziness and nausea caused by levofloxacin ). Along with these medicine take some ambroxol type cough syrup , it will facilitated mucus from lungs . Since these are prescription drugs , so consult a physician and take prescription. Hope this will help you . In my opinion this treatment will cure you within 5 days but if no relief then consult a pulmonologist and get his opinion. Good luck.