I have had CF and Fibromyalgia for over 8 years and hope a couple of things that helped me will help others. I am not going into symptoms and all I've been through. Just want to give people a couple options to talk over with your doctor.
I first took cymbalta, and it didn't help me much. My doctor found a new drug 6 years ago that was the first one made for this called Savella. I noticed an improvement immediately but it was still a long slow journey to feeling better. It got me out of bed and able to attend family functions. Eventually I was able to run 5ks, take care of myself and my home, and have a life. Don't know if it's an option for everyone, but it made a huge difference to me. I started out at the maximum dose of 200 mg and worked my way down to 50 mg.
about 8 months ago I did way too much and relapsed. I had to go back up to 200 mg. I discovered from internet research that we process oxygen differently than others and need to stay below the anaerobic threshold at all times. You can keep this under control by keeping your heart rate low. For some people this may be 95 and for others it could be 107. I bought a heart rate monitor and went to stay with my daughter. I did absolutely nothing but go for 2 or 3 mini-walks (1/4 to 1/2 mi) a day, take naps, and sleep till I felt like getting up. After about 2 weeks I was able to walk about 40 minutes. I did not do anything else.
I am back home now and have lowered my dose to 100 mg. I keep my heart rate below my anaerobic threshold at all times. I cannot mow my lawn with a push mower because it raises my heart rate too high and I become sick for days, so I use a rider and my family does the trim work. I can now walk 4 miles at a much faster pace and still maintain the same heart rate. I have signed up for a 5k in January and hope, by that time, to be able to run most of it at that same heart rate. According to the 'Maffetone Method' if you continually maintain a steady heart rate you can work up from barely walking to running at the same heart rate.
I firmly believe that if you stay inactive and because of the problem with oxygen intake you will continue to become sicker. I started feeling better the minute I started a consistent regimen of walking and resting.
It took me 8 years to learn what I should have learned the 1st year about keeping intensity low. I thought I felt better and I could conquer the world. So even when you're feeling better keep your heart rate low and build up duration and fitness. Hope this helps someone.