Definately get a second opinion.
The lungs will try to expel any undesired object, even if it is a benign growth. Even a benign growth could potentially set you to a chronic cough, but definately get it checked (I'm not a medical doctor, for the record).
I had a spot on my lung about 3mm found about a year ago during a CT scan. They checked it six months later and it's still 3mm. I think it is just something to keep an eye on and nodules are not that uncommon.
As for the cough, my family has been going through it for about six weeks now. I started with my husband, then my kids and now me. Of course, I think I have the worse cough of all of us. Nights are the hardest for me too. I cough all night long. It hurts so bad to cough, my head hurts--my chest hurts and I don't seem to be getting any thing up when I finally deep cough. None of us had fever or any related symptoms. I feel horrible with the cough but my doc says it is going around and some people have it for 2-3 months. If there is no fever, chills or flu like symptoms, it should be okay. That is what she said anyway.
I think if you are nervous about it, go to the pulmonary specialist (TAKE YOUR SCANS!!) and get his opinion. You won't rest until you are comfortable with a diagnosis. (I know!!)
Greatly agree with above poster. If your doc was not a pulmonary doctor go to on get a second opionion to ease your mind. wish well
Maybe you could get a second opinion from a Pulmonary specialist. Just get copies of your films/reports and get a referral if necessary.