My son who’s one has cough for the last two months and the doctor says all is well. What should I do?

It says here to take your child to the doctor if the cough persists for more than a month. http://sg.theasianparent.com/your-kids-cough-what-you-need-to-know/3/ Since 2 months seems a bit long, I would get a second opinion, just to be sure.