2 weeks cough now..on 3 days i go to doctor and give medicine..after 7 days still coughing and go to another doctor.but still going to 2 weeks still coughing.in the whole day less cough but at night and in early morning continous cough?

Cough especially at night and early in the morning can be caused by things other than infection. An asthma type reaction to an earlier infection can cause this and so can acid reflux that occurs more at night (which you may not have any other symptoms). You need to make sure you are assessed for both of those. Need to followup with a doctor to reasses that.