What Is The Treatment For Persistent Cough?

I am suffering from serious cough last a month and half. Started with congestion. Now its all gone, throat nose everything is clear. But the problem is when i cough comes, i cant stop. it keeps coming and when i cough very minute white sputom comes which is white in color.

When sleeping no cough, this is become irritant and uncontrolled cough.

Please please help me. I am fed up.