Hi, I'm a pharmacist. I'm guessing the response with the chewable pill is Singulair NOT Advair. Advair is an inhaler for asthma and Singulair is a leukotriene inhibitor used for asthma or allergies. It comes in a chewable pill for kids. I myself have reactive airway and I develop a lingering cough for a month or 2 after a bad upper respiratory cold. Yes, this COULD be the case, it COULD be allergies, it COULD be a lot of things. There are a lot of colds and flu going around and sometimes it takes a long time to get over these things especially when you're a little guy....I have a 15 month old and we are getting over the flu as I type this!! Try a vaporizer/humidifier at night in his room. It seems to be helping my little guy with his cough. Reflux is another cause of chronic cough but is most likely not the case in your situation. As far as great doctors in the Twin Cities area, I absolutely LOVE Southdale Pediatrics. All the of doctors I have been to there are great...we go to the one in Eden Prairie. We have seen Dr. LeFevre, Dr. Lawler, Dr. Laville, and Lisa Kroening. I've filled their scripts for years in practice and they are just terrific doctors!!! They also have an allergy clinic there. Don't stress :) Good luck!!!