How long can residual cough last after obstructive bronchitis and how did…

How long can residual cough last after obstructive bronchitis and how did you treat it? They told me the lungs were clean, do nothing. It's been 5 weeks now, I still have a cough. But today it seems to be a little more. The doctor said to take tests tomorrow, although they were done about 10 days ago, everything was normal.