Morton's neuroma: This condition is characterized by a benign growth of nerve tissue in the foot, commonly between the third and fourth toes, but can also occur near the large toe. It causes pain, numbness, or tingling, especially when walking or wearing tight shoes. The patient's age and symptom location make this a plausible diagnosis.

Peripheral neuropathy: Although the patient is non-diabetic, peripheral neuropathy can result from various causes, including vitamin deficiencies, alcohol abuse, or exposure to certain toxins. It often presents with numbness, tingling, or pain in the extremities.
Tarsal tunnel syndrome: This condition involves compression of the posterior tibial nerve as it travels through the tarsal tunnel on the inner side of the ankle. Symptoms can include numbness, tingling, or burning sensations in the foot, which could potentially affect the large toe.
Gout or pseudogout: These conditions can cause sudden, severe pain and swelling, often starting at the base of the big toe. However, the absence of erythema or warmth in this case makes these diagnoses less likely, though not impossible, especially if the patient is in a period between acute attacks.

Erythromelalgia: A disorder characterized by burning pain, heat, and redness in the hands and feet. Although the patient does not exhibit erythema or warmth, erythromelalgia can have variable presentations, and missing this diagnosis could lead to significant morbidity due to its association with myeloproliferative disorders.
Peripheral artery disease (PAD): While PAD typically presents with claudication (pain in the legs or arms during exercise), in severe cases, it can lead to rest pain, often described as burning or aching in the toes. The absence of typical claudication symptoms does not rule out PAD, especially in a patient of this age group.
Neoplastic processes: Rarely, a tumor (either benign or malignant) could cause nerve compression leading to the patient's symptoms. Although unlikely, missing a neoplastic process could have severe consequences.

Complex regional pain syndrome (CRPS): A chronic pain condition characterized by severe, burning pain at the site of an injury, typically an arm or leg. It can also involve changes in skin temperature and color. While CRPS is rare and usually follows an injury, its presentation can be varied.
Friedreich's ataxia: A rare genetic disease that causes progressive damage to the nervous system, resulting in symptoms that include numbness or tingling in the hands and feet. Given the patient's age and the late onset of symptoms, this diagnosis is highly unlikely but is mentioned for completeness.
Leprosy (Hansen's disease): A chronic bacterial infection that primarily affects the skin, nerves, and mucous membranes. It can cause numbness, tingling, or burning sensations in the extremities. Leprosy is rare in many parts of the world but should be considered in patients with a history of travel to or residence in endemic areas.