Big unmumsnetty hugs
I think your DD is getting to that inevitable stage in the illness where the realisation of how life has changed is hitting. Coming down with a chronic, life altering illness is in many ways equivalent emotionally to the grieving process- you go through all sorts of emotions like anger, sadness, denial before eventually finding acceptance. You will both get there but it is a long and hard journey.
I reacted exactly the same as your DD; to start with you feel so poorly you don't give it much thought and just try to get through each day, but after a few months you do start to worry you will never improve and it hits how dramatically your life has stopped. I cried, I self-harmed, I thought about taking my own life, I sunk into a deep depression… it was a horrible time and one I would not wish on anyone. But with support and help I did get through it and eventually I came out of the other side. I can relate to wanting it to end- I used to lie in bed just thinking what is the point? One of the things that helped me enormously though was the strength and positivity of my mum. In truth she had no idea what was going to happen and if I'd ever get my life back, but she never showed it in front of me. As hard as it is try not to show to your DD how worried you are; it doesn't matter how old we get, we still want our parents to say it will be okay! Listen to her and comfort her but if possible don't reveal your anxieties, find other support in order to stay strong for her.
I really, really would urge you to get her to sign up to ayme if she hasn't already. It was one of the things that got me through my first relapse and I have so many wonderful friends from it. You may find the helpline useful too for advice about specialists and school. They are incredibly knowledgeable about these things. There are many Facebook groups as well for people with CFS. I will message you my email address and if she ever wants someone to natter to then please tell her she is welcome to contact me anytime, I used to moderate on the ayme board so I have tried to address pretty much every problem members have had at one point or another! (not sure how successfully mind you
). I also know several people of her age that I met through ayme but have now left who would be more than happy to chat.
Stay strong, it is awful but it can and most likely will get better. I know of people who were bed bound for years who now work full time, several girls who are married and have babies, someone who was unable to talk and eat who is now at uni. There are a lot of positive stories, it just feels like it will last forever (obviously some people never recover fully, but many lead a reasonably full life). Before this latest relapse I got myself well enough to go on holidays, move out, get married, go swimming and roller blading, have a part time job etc. There is always hope 