Thank you everyone for your answers!.
I think sometimes I warry too much, but as you know he has been diagnosed this year and I guess I have to get used to it <img src="i/expressions/face-icon-small-smile.gif" border="0"> . I cannot help paying much more attention to his symptons now that I know the diagnosis.
The truth is that overall he has been feeling much better this year, after starting specific cf treatment. In fact he was without antibiotics from March till Novermber. I guess winter is not good for cf. Looking foward for summer to come back! Or maybe will have to go to live to a sunny beach on the south of spain <img src="i/expressions/face-icon-small-smile.gif" border="0">