Stasis Dermatitis: This condition is characterized by skin inflammation and discoloration due to poor circulation, which aligns with the patient's symptoms of bilateral lower extremity edema, redness, and a stinging sensation when touched. The patient's age and presentation make this a highly plausible diagnosis.

Cellulitis: An infection of the skin and subcutaneous tissues, which could explain the redness, swelling, and pain. The stinging sensation could be due to the infection causing nerve irritation.
Eczema (Dyshidrotic or Nummular): Certain types of eczema can cause red, itchy, and swollen patches on the skin, which might fit the patient's symptoms, especially if the stasis dermatitis is considered in conjunction with or as a precursor to eczematous changes.
Contact Dermatitis: Given the patient's discomfort with clothing touching the affected area, an allergic reaction or irritant contact dermatitis could be a contributing factor, especially if new soaps, detergents, or fabrics are introduced.

Deep Vein Thrombosis (DVT): Although initially not suspected, DVT is a critical diagnosis to rule out due to its potential for severe complications, such as pulmonary embolism. The presence of edema and redness could be indicative of a DVT, especially in an elderly patient.
Necrotizing Fasciitis: A severe infection that affects the tissue beneath the skin and the fascia, a layer of tissue covering muscles. It's a medical emergency and could present with severe pain, swelling, and redness, making it crucial not to miss.
Chronic Venous Insufficiency: This condition can lead to edema, skin changes, and potentially ulcers. It's essential to consider, given the patient's age and symptoms, as it might require specific management to prevent progression.

Lymphedema: A condition characterized by swelling in one or more extremities, resulting from impaired flow in the lymphatic vessels or lymph nodes. It could be a consideration if the edema is disproportionately severe or if there's a history of cancer treatment.
Erythromelalgia: A disorder that causes burning pain, heat, and redness in the hands and feet. It's less common but could be considered if the patient's symptoms are primarily related to heat, redness, and burning sensations.
Panniculitis: Inflammation of the subcutaneous fat, which can cause painful nodules or plaques and might fit the patient's description of stinging sensations and swelling, although it's less likely given the bilateral and symmetric nature of the symptoms.