How do I find out what is really bothering my spouse if she has fibromyalgia?

No. You can persist. Menopause bring problemsfrom sleep and this can aggravate fibro. Persistence depends on the individual it is made worse with poor sleep, poor control of stress and psychological issues and lack of exercise. Look for control of these for resolution.
Listen & believe her. Finding out what is bothering a spouse with fibromyalgia is tough, since patients with fibromyalgia often feel misunderstood. The pain they suffer is invisible to others & often underestimated. They are often judged as hypochondriac or lazy due to pain and fatigue. Take time & listen to your spouse, empathize & validate her symptoms. She needs your love & support, & she needs you to believe her.
Evaluation. ? how to discover underlying cause in fibromyalgia (FM) sufferer. My opinion is that a major causal factor in this multifactorial disorder is musculoskeletal injury w. chronic widespread muscle spasm. An Osteopath is best medical specialist to evaluate. Aquatherapy, gentle yoga, walking, & tai chi best ways to rehabilitate; during pain honeymoon from Acupunture, massage, trigger point injections.