How To Treat Chronic Cough Inspite Of Taking Cephalexin And Prednisolone?

Been coughing since christmas..have 2 course antibiotics cephalexin..not relieved..doctor put me on esenoprazole not relieved. Put me on prednisolone for 3 days...cough still persist..im on atacand 4 mgs daily for 2 years..ultrasound to thyroid throat all clear..all moist and dry cough syrup tried...cough persist..blood test nuetrophils ..no signs of infection...does atacand have side effect after prolong use...