I went through my childhood with a lot of digestion-related problems. I had gotten sick, colds, pneumonia, etc. quite frequent as well, and my mom and her mom kept saying there was something wrong, but everytime I was taken to a doctor, they kept saying different.
Then, finally, at about the age of 7 and a half, my younger sister was born, but she was born with some complications, which had a few nurses come by for post-trauma follow-ups. After my mom started talked with them about my sister, she started telling them about my problems. They took a look, poking me around here and there, then with a suspiscion of CF, had reffered me to their CF clinic at the Children's hospital. Myself, and my siblings were all tested with the sweat test, and I was the only one who passed it (or failed it, whichever suggests I was the only one with CF.)
(P.S. PepperKitty, that was a good and short description!! Wow!)