35,F,c/o refractory dry cough since a month more in the evening hrs.not asso with fever,wt loss etc. bronchodilators,antibiotics, antihistaminics, Rx for GERD,given.routine lab,IGE,ESR,Ab E counts normal.PFT,ECHO normal.not on any chronic medications. RS clear, CT thorax and cxray displayed. plz sugg further management.