Chris, good evening I hope you are well and having a great night.  With regard to your question, consider the following as it pertains to Fibromyalgia. 

Fibromyalgia means pain in the fibrous tissues. It is felt in the skeletal muscles, tendons, and ligaments throughout the body, but at times can actually affect the viscera and smooth muscle tissue. Unlike arthritis, the joints of the body are not directly affected and joint pain and swelling usually are not present. You need to minimize or eliminate the chronic fatigue/pain cycle. 

Tips for training would be; use heat prior to beginning exercise, use extended and slower warm-ups, progress gradually to higher intensity work, gentle to moderate intensity exercise is well tolerated, avoid high impact, high intensity exercise and modify the exercise when necessary.

We hope this helps.  Please keep us updated to how your boyfriend's mom progresses.