Growing Pains: This condition is common in pre-teen children, characterized by recurrent pain in the legs, typically in the knees, elbows, and ankles, without any history of trauma. The pain often occurs at night and can be relieved by massage or over-the-counter pain medications.

Osgood-Schlatter Disease: A condition that affects the knee, causing pain and swelling below the kneecap. It's common in adolescents during growth spurts and is related to overuse or repetitive stress from sports.
Osteochondritis Dissecans: A joint condition in which a piece of cartilage, along with a thin layer of the bone beneath it, comes loose from the end of a bone because of inadequate blood supply. It can cause pain and swelling in the affected joint, such as the knee or elbow.
Juvenile Idiopathic Arthritis (JIA): A chronic autoimmune disease that causes joint inflammation and stiffness in children. It can lead to pain, swelling, and limited range of motion in the affected joints.

Cancer (e.g., Osteosarcoma, Ewing's Sarcoma): Although rare, bone cancers can present with pain in the bones or joints. Early detection is crucial for effective treatment.
Infection (e.g., Osteomyelitis, Septic Arthritis): Bacterial infections can cause severe pain, swelling, and redness in the affected limb. Prompt diagnosis and treatment are essential to prevent long-term damage.
Sickle Cell Disease: A genetic disorder that can cause episodes of pain due to vaso-occlusive crises, which might affect the bones and joints.

Ehlers-Danlos Syndrome: A group of disorders that affect connective tissues supporting the skin, bones, blood vessels, and many other organs and tissues. It can lead to joint hypermobility and pain.
Stickler Syndrome: A genetic disorder that can cause problems with the joints, among other issues, due to its effect on connective tissue.
Gaucher's Disease: A genetic disorder that can lead to bone pain and other systemic symptoms due to the accumulation of harmful quantities of a certain fat (lipid) throughout the body.