Fibromyalgia: A chronic condition characterized by widespread musculoskeletal pain, fatigue, and tender points. It is a common cause of diffuse joint pain, especially in middle-aged women.

Osteoarthritis: A degenerative joint disease that can cause pain and stiffness in multiple joints, especially in older adults.
Rheumatoid Arthritis: An autoimmune disorder that causes inflammation and pain in multiple joints, often symmetrically.
Lupus: A systemic autoimmune disease that can cause joint pain, fatigue, and other symptoms.
Hypothyroidism: A condition where the thyroid gland does not produce enough thyroid hormones, leading to joint pain, fatigue, and other symptoms.

Septic Arthritis: A bacterial infection of the joint that can cause severe pain, swelling, and fever. If left untreated, it can lead to joint destruction and sepsis.
Lyme Disease: A bacterial infection transmitted by ticks that can cause joint pain, fever, and other symptoms. If left untreated, it can lead to serious complications.
Cancer: Certain types of cancer, such as multiple myeloma or lymphoma, can cause diffuse joint pain.
Vasculitis: Inflammation of the blood vessels that can cause joint pain, fever, and other symptoms. If left untreated, it can lead to serious complications.

Ehlers-Danlos Syndrome: A group of genetic disorders that affect the connective tissue, leading to joint hypermobility and pain.
Relapsing Polychondritis: A rare autoimmune disorder that causes inflammation of the cartilage and joints.
Sjögren's Syndrome: An autoimmune disorder that causes dryness of the eyes and mouth, as well as joint pain and other symptoms.
Sarcoidosis: A condition that causes inflammation of the lungs, lymph nodes, and other organs, leading to joint pain and other symptoms.