What Causes Persistent Cough Despite Taking Antibiotics?

I got sore throat and 3cough in December. I took 3 different antibiotics. However my throat got better in Jan but urge to cough remained. I dont have pain or fever from last 2 months but I still have cough and I have to cough to take it out. I have shown to EnT as well as Pulmonogist who took chest and sinus xray and there was nothing. However my cough is not going. Whom should I consult.