Investigators are constantly looking at various explanations for the occurrence of fibromyalgia. Some experts are exploring hormonal disturbances and chemical imbalances that affect nerve signaling; others believe fibromyalgia with its deep muscle pain is linked to stress, illness, or trauma. Other theories include a possible hereditary cause. But while there is no clear consensus about what causes fibromyalgia, most researchers believe fibromyalgia results not from a single event but from a combination of many physical and emotional stressors.
Some have speculated that lower levels of a brain neurotransmitter called serotonin leads to lowered pain thresholds or an increased sensitivity to pain. It's associated with a calming, anxiety-reducing reaction. The lowered pain thresholds in fibromyalgia patients may be caused by the reduced effectiveness of the body's natural endorphin painkillers and the increased presence of a chemical called "substance P." Substance P amplifies pain signals.
There have been some studies that link fibromyalgia to sudden trauma to the brain and spinal cord. But currently, all theories about what causes fibromyalgia are merely speculative.

Besides the immediate pain caused by fibromyalgia you may be experiencing several related symptoms, and in some cases these other symptoms may even be more troublesome. Some of these symptoms may include fatigue, unrefreshing sleep, poor concentration, short-term memory disturbance, sleep disturbance, morning stiffness, dizziness and sensations of numbness or tingling in the extremities.
When looking at large populations, many other illnesses often coexist with fibromyalgia. First, anxiety, depression and other mood disorders are much more common in patients with fibromyalgia than in the general population, but many patients with fibromyalgia do not have mood disorders. Many patients Patients with fibromyalgia could also have headaches, irritable bowel syndrome, TMJ syndrome, a painful bladder condition called interstitial cystitis, chronic pelvic pain, chronic fatigue syndrome and autoimmune diseases such as lupus and rheumatoid arthritis.

Widespread pain is characteristic of more than 97%of patients with fibromyalgia. Unlike the joint pain of osteoarthritis, fibromyalgia pain is felt over the entire body. The pain can be sharp, dull, throbbing or aching and is felt in the muscles, tendons, and ligaments around the joints. For some people with fibromyalgia, the pain comes and goes. The pain also seems to travel throughout the body.
Along with the deep muscle soreness and body aches, people with fibromyalgia have painful tender points or localized areas of tenderness around their joints that hurt when pressed with a finger. It's the tissue around the joints rather than the joints themselves that hurts. These tender points are often not areas of deep pain. Instead, they are superficial, located under the surface of the skin.

The location of tender points is not random. They are in predictable places on the body. If you apply pressure to tender points on a person without fibromyalgia, he or she would just feel pressure. For a person with fibromyalgia, pressing the tender points is extremely painful.