Which condition is characterized by muscle pain and fatigue throughout the body?

Fibromyalgia is a condition that is specifically characterized by widespread muscle pain and fatigue throughout the body. Individuals suffering from fibromyalgia often experience not only chronic pain but also other symptoms such as sleep disturbances, cognitive difficulties (often referred to as "fibro fog"), and heightened sensitivity to pain. The widespread nature of the discomfort is a key feature that distinguishes fibromyalgia from other conditions.

Osteoarthritis primarily affects the joints and is characterized by localized pain and stiffness in those areas, rather than systemic muscle pain. Migraines are severe headaches often accompanied by nausea, vomiting, and sensitivity to light or sound; they do not typically involve body-wide muscle pain. Stomach ulcers are lesions that develop in the lining of the stomach, leading to localized abdominal pain, but they also do not involve muscle fatigue or chronic pain throughout the body. Therefore, fibromyalgia is the most accurate choice that matches the condition described in the question.