We all have fibro fog; we can't remember if this has been discussed before or not!
Seriously, I do know what you are talking about. Some days I feel fine, and others, I feel like I've been hit by a truck. Sometimes I can relate it to over-doing something, but often, there is no rhyme nor reason. I've even gone through periods where I've wondered, "Do I even have fibro?" but then the pain and fatigue will hit full force, and my doubts definitely go away.
Like others have mentioned, I just try to pace myself, even on the days I'm feeling okay. I try to save my energy for the things that are important like work or an outing with my family, and I try to enlist all the help I can get with the unimportant stuff (like house cleaning, etc.). The things I can't get immediate help with (like cleaning my carpet or windows) I just try to ignore until I can get help or afford to pay someone to do it.
Fibro is such an unpredictable force, and it is different for everyone.
BTW, my daughter is a dancer too.
Hugs - Austen
"There is no charm equal to tenderness of heart." - Jane Austen
Fibromyalgia, 2 back surgeries, Meniere's Disease, 30+ kidney stones, GERD, IBS, Asthma, Allergies, Endometriosis, Heart Arrythmia, Myofascial Pain, TMJ, Bi-lateral sacroiliitis.