My mom is 65 years old she is a known case of diabeties for 10-12years ..had a minor heart attack 10years back.... she is allergic to dust having asthmatic allergy... rightnow she is taking tab.calan80mg OD , tab.glucovance500mg OD ,tab myteka 10mg OD, tab.kestine10mg OD and a evohaler name seritide25/250mcg ...she nebulize on n off with atem n normal saline... she has gone through all the baselines all are normal even TB is negative ... her cough is not going away for months .. what u suggest?