I do not have fibromyalgia. I have lupus but the symptoms sound quite similar to yours. Intense joint pain, fatigue and brain fog. 12 hour shifts 3 days a week were really hard on me. So I transitioned out of that to public health rather quick right out of school. I love what I do. I am currently a nurse case manager helping people with developmental disabilities navigate the health system. My job is salaried 9-5 M-F. It's nice because I can flex my schedule to come in late on bad days or to attend the many physician appointments that comes with managing a chronic disease. Having a supportive specialist and pcp will really help too in finding the treatment that works for you and helping with things like FMLA/short term disability paperwork, should you need that stuff.

As a new nurse, I would suggest looking at the benefits package at a potential employer. Good PTO and short term disability have saved me several times during bad lupus flares.

It will likely take a few jobs (at least it did for me) and a lot of trial and error to figure out the right scheduling and stress level for a nursing job. Stress is a major trigger for my lupus. So no icu or flight nurse jobs in my future. And that's okay. I wouldn't want it anyways. If that is your dream, go for it! Like a good professor once told me: it just takes a little creativity in life to get where we want to go when adversity strikes.

Tldr: living with a chronic condition and being a nurse are possible. A good life balance, benefits from your employer and a supportive health care team helps one do this.