Plantar Fasciitis: This is the most common cause of heel pain, resulting from inflammation of the plantar fascia, a band of tissue that runs along the bottom of the foot. It is often associated with overuse, poor foot mechanics, or obesity.

Achilles Tendinitis: Inflammation of the Achilles tendon, which connects the calf muscles to the heel bone, can cause heel pain, especially in athletes or individuals who have recently increased their physical activity.
Heel Spurs: A bony growth on the underside of the heel bone, which can cause pain when walking or standing, especially if the spur is large enough to irritate surrounding tissues.
Bursitis: Inflammation of the bursae, fluid-filled sacs that cushion bones, tendons, and muscles near joints, can cause heel pain, especially if the bursae near the heel become inflamed.
Fat Pad Atrophy: Thinning of the fat pad under the heel can lead to heel pain, as the natural cushioning is reduced, making each step more painful.

Calcaneal Stress Fracture: A small crack in the heel bone, which can be extremely painful and may not be immediately visible on X-rays. Missing this diagnosis could lead to further injury or complications if not properly treated.
Infection (Osteomyelitis or Septic Arthritis): Infections of the bone or joint near the heel can cause severe pain and have serious consequences if not promptly treated with antibiotics.
Tumor: Although rare, tumors such as osteoid osteoma or other bone cancers can cause heel pain and must be considered to ensure timely diagnosis and treatment.

Rheumatologic Conditions: Conditions like rheumatoid arthritis, psoriatic arthritis, or ankylosing spondylitis can cause heel pain, though they are less common causes.
Nerve Entrapment: Entrapment of nerves in the foot, such as the posterior tibial nerve, can cause pain in the heel area.
Paget's Disease of Bone: A chronic condition that can result in enlarged and misshapen bones, potentially causing heel pain due to bone deformity or fracture.