Plantar Fasciitis: This condition is characterized by inflammation of the plantar fascia, leading to pain and swelling in the heel. The pain typically worsens with movement and improves with walking, which matches the patient's symptoms. Morning stiffness is also a common complaint.

Achilles Tendinitis: Inflammation of the Achilles tendon can cause pain and swelling in the back of the heel, which may radiate to the thigh upon movement. While it's more common in athletes, it can occur in anyone.
Bursitis: Inflammation of the bursae around the heel can cause swelling and pain, especially with movement. The pain can radiate and worsen with activity.
Heel Fat Pad Atrophy: This condition involves the thinning of the fat pad under the heel, leading to pain and discomfort, especially when walking or standing.

Bone Tumor (e.g., Osteosarcoma): Although rare, bone tumors can cause progressive swelling and pain that worsens over time. It's crucial to consider this diagnosis to avoid delayed treatment.
Infection (e.g., Osteomyelitis): Infections of the bone or soft tissue can cause swelling, pain, and redness. These conditions require prompt treatment to prevent serious complications.
Deep Vein Thrombosis (DVT): While less common in the context of heel swelling, DVT can cause swelling and pain in the leg, which may be exacerbated by movement.

Erythromelalgia: A rare disorder characterized by burning pain, heat, and redness in the hands and feet, which could potentially cause heel swelling and pain.
Sarcoidosis: A condition that can cause inflammation in various parts of the body, including the bones and joints, leading to swelling and pain.
Gout or Pseudogout: Although more commonly associated with the toes, these conditions can cause sudden, severe pain and swelling in other joints, including the heel.