I have had my fibromyalgia diagnosis for about six months now. While it has been only been six months since my diagnosis I most likely have had it much longer. I believe I have noticed symptoms since 2016 if not longer. There is no cure for fibromyalgia and very little medical treatment. It is a condition you learn to live with the best you can with lifestyle changes.
In order to live with a chronic illness such as fibromyalgia one must grief for the life before but then move through the steps of grief and live a life of acceptance. That doesn't mean one does not seek medical treatment or look for ways to live better with fibromyalgia. But that does mean live today the best one can and finding peace with what one has been given.
I strongly recommend the book, Good Grief by Granger E. Westberg. It is a small book that explains the process of grief and each of the steps. The author helps one to identify where they are at and what comes next.
Once one knows what grief is and the process they can move towards healing and living with the loss one has had.