I am new to this board, but had a problem with depression and anxiety a while ago. I am not a doc, and always suggest if depression is building to seek professional treatment because the problems may intensify.
In a book I read that it is important to get back to your normal functioning positive level soon after you get depressed. Unfortunately depression tends to pull you down deeper as it tugs away at you, so unless you are able to find a way to surface quickly each time, it can build up its strength and hold you down to ever lower depths. True depression and its often interconnected partner anxiety are not the things to tackle alone after they progress to a certain state.
My mood required meds for 9 months as I eventually had anxiety and depression images flashing into my mind every minute, and there was no way for me to find the energy to focus on anything else, although I was able to maintain a job. (If there was a reality TV show with the world's worst workers as contestants, I could have won.) The meds served their purpose and I was able to quit them 4 months ago and live a happy life. Through meds and a change of Outlook, I was able to focus my mind to be as a log floating in a river, not averse to the bank of unhappiness because it is unavoidable at least some of the time, nor crave the bank of happiness because it is not possible to stay happy all the time either. Staying in the middle of the river and sort of floating to the ocean of peace is the best expectation for a person to strive for. I just borrowed this idea from of part of an ancient Indian philosophy, (Buddhism) but interestingly it is similar to cognitive behaviour therapy designed in recent years to help depressed people. Apparently mindfullness based cognitive behaviour therapy (mbct) is even closer to the old philosophy. mbct is designed to help depression sufferers relieved of their depression and then off meds to avoid a relapse.
So if you are concerned, it is best to seek professional advice. I hope meds are not necessary in all your cases, but in some cases they are so you need to be aware of that.
My 45 year old brother has needed professional attention for 15+ years but my mother will not face up to it. (Maybe it is pride of ownership.) My mother tried to protect my him all his life by financing his hopeless business schemes where he mopes in front of a computer for a few hours a year. She says anything to pretend that he was functioning. Please accept that if your child is depressed over cf, sending him to a professional may be helpful and is not a sign of weakness.
Cognitive behaviour therapy that I mentioned is something your doc might talk over with you as an option. (The only reason I put the whole Buddhism part in is I have never read cognitive behaviour so had to stick to what I knew.)
I spend a lot of time on depression forums at another board and have learned a lot from reading and the posts of the group. Unfortunately, that site does not have a cf chat group and because I wanted to help cf people I am here.
Feel free to inbox me or reply to this thread.