Postoperative pain: This is the most likely diagnosis given the recent surgical intervention. Pain after surgery is a common and expected outcome due to tissue trauma and the healing process.

Infection: Despite proper wound care and debridement, infection can still occur, especially in the context of an amputation. Signs of infection such as redness, swelling, warmth, and purulent discharge should be monitored.
Neuroma formation: After amputation, the formation of a neuroma (a growth of nerve tissue) at the stump can cause pain, especially if it becomes irritated or entrapped.
Stump complications: Issues such as pressure sores, inadequate healing, or a poorly fitting prosthetic can lead to pain and discomfort in the stump area.
Complex Regional Pain Syndrome (CRPS): This condition, formerly known as reflex sympathetic dystrophy, can occur after trauma or surgery, leading to chronic pain, swelling, and changes in skin temperature and color.

Deep Vein Thrombosis (DVT): Although less common in the post-amputation limb, DVT can occur and is a potentially life-threatening condition if not recognized and treated promptly.
Osteomyelitis: Bone infection can be a complication of the initial wound or the amputation surgery itself, requiring aggressive treatment to prevent further complications.
Gas gangrene: A rare but deadly infection caused by Clostridium perfringens, which can rapidly progress and is more common in wounds with poor blood supply.

Erythromelalgia: A disorder characterized by burning pain, heat, and redness in the affected limb, which can be a complication of various conditions, including diabetes and myeloproliferative disorders.
Chronic pain syndromes: Such as phantom limb pain, which can be challenging to manage and may require a multidisciplinary approach for effective treatment.
Nerve entrapment syndromes: Conditions like peroneal or tibial nerve entrapment can cause pain and should be considered, especially if the pain has a specific distribution or exacerbating factors.