Fibromyalgia: This condition is characterized by widespread musculoskeletal pain accompanied by fatigue, sleep, memory, and mood issues. The pain often migrates and can be exacerbated by various factors including stress and weather changes. Given the description of widespread migrating pain, fibromyalgia is a plausible diagnosis due to its prevalence and the nature of its symptoms.

Rheumatoid Arthritis (RA): An autoimmune disorder that can cause widespread pain, stiffness, and swelling in the joints. The pain can migrate as different joints become affected over time. Early diagnosis is crucial for effective management.
Lupus: A chronic autoimmune disease that can affect various parts of the body, including the joints, skin, kidneys, and other organs. It often presents with migrating joint pain, among other symptoms like skin rashes and fever.
Thyroid Disorders: Both hypothyroidism and hyperthyroidism can cause widespread muscle and joint pain. The pain can be migratory and is often accompanied by other systemic symptoms such as changes in weight, energy levels, and bowel habits.

Multiple Myeloma: A type of blood cancer characterized by the proliferation of malignant plasma cells in the bone marrow. It can cause widespread bone pain that may seem to migrate as different areas of the bone are affected. Early detection is critical for treatment.
Osteomyelitis: An infection of the bone, which can cause severe, migrating pain if the infection spreads to different bones. It's a medical emergency requiring prompt antibiotic treatment.
Vasculitis: Inflammation of the blood vessels, which can cause a wide range of symptoms including migrating pain due to the involvement of different vascular territories.

Ehlers-Danlos Syndrome: A group of disorders that affect connective tissues supporting the skin, bones, blood vessels, and many other organs and tissues. Some types can cause widespread and migrating joint pain due to hypermobile joints and tissue fragility.
Sarcoidosis: An inflammatory disease that affects multiple organs in the body, but can cause migrating pain if it affects the bones or joints. It's rare and often presents with other symptoms like lung issues or skin lesions.
Relapsing Polychondritis: A rare disease characterized by recurring episodes of cartilage inflammation. It can cause migrating pain as different cartilaginous structures (like the ears, nose, or joints) become involved over time.