Could it be CF in my 14 yo?

My son is 14 years old, weighs 78 lbs and is 4'10". He has had a cough for 2 years now and asthma among other things have been ruled out. He has had pneumonia twice and bronchitis once in this time. He is currently under the care of an endocrinologist because of his growth issues. He is falling farther and farther behind. His latest labs show his FSH to be very low and his LH to be low but not out of range. His vitamin D level continues to stay low despite supplements for the last year. It is currently at 21. He has always struggled with constipation and very large BM's. As an infant he had the same cough he has now that lingered from about the age of 8 months to 2 years. He suffered with chronic constipation as an infant that would have him screaming for hours. I terrified that this could all be CF. I tasted his skin to see if he tasted salty (he thought I was nuts!) but he doesn't. Any opinions? I'm freaking out right now! Thanks so much!
Source: Cystic Fibrosis Newly Diagnosed Forum - Category: Respiratory Medicine Authors: Tags: Newly Diagnosed Source Type: forums