FMS can be secondary to other autoimmune disease. And in that case, treatment of underlying disease and FMS, both should be treated

Fibromyalgia can be treated but it is a slow and patience requiring process. Apart from medicine (1 of which is Fluoxetine), exercise and stress relief/ counselling are also important for treatment. Based on the report, your mother may be suffering from Sjogren's syndrome in addition. Detailed history and a few investigations will be required for confirmation