Jennifer, just found your thread. Hang in there, good to know your DS is being properly treated. My DS started coughing when he was 16, and the GP kept prescribing syrups and stuff, and I finally got mad at him and found a pulmonologist, who sent for a cat scan, and since there were no bronchiectasies sent for more tests (lung function, sweat) and since the sweat was 50 he suspected CF and arranged for a specialists's appt. By then my son was 18 already. He's now 20 and being medicated for CF. The genetic test was negative for common mutations, so recently they sent him for a new test (rectal biopsy) which I think works similarly to the nasal test (the lab doctors actually see how the chlorides behave in the cell) and yes his chlorides correspond to CF, so this is it. I hope everything turns out Ok for your son, with the right medication.