Hi Kelly,
Everyone's symptoms tend to be different, and they can vary according to the genes, your age, your compliance, etc.
For example, my cough is not very productive and others will be coughing stuff up all of the time. I have more of an asthma cough.
I have a constant problem, year round, with my sinuses as the Pseudomonas keeps growing there, then drains to my lungs, so I have to be aggressive in treating that.
I'm not sure if your lad is culturing PA or what, but once you start culturing those you have will have worse times than others. I will feel pretty good and then as it builds up I have a harder time ("flare up" as you put it) and have to do IV's to cut the bacteria back and then I'm okay for about 6 mos. Some people don't need to do IV's for years and some every few months, it varies.
My pancreas has just in the last year been deemed "Moderately insufficient" so I can't answer much on the bowel symptom, but hopefully someone else will.