Dependent edema: This is the most likely diagnosis given the patient's hemiplegic status, which leads to decreased mobility and dependency of the affected limb, causing fluid accumulation and swelling. The fact that the patient is holding his Plavix (an antiplatelet medication) suggests that there might be concerns about bleeding, but it doesn't directly point towards a DVT.

Deep Vein Thrombosis (DVT): Although the patient is on Plavix, the risk of DVT is still present, especially in a post-stroke patient with decreased mobility. Symptoms such as swelling, warmth, and discoloration of the affected limb could be indicative of a DVT.
Cellulitis: This is an infection of the skin and subcutaneous tissues, which could present with swelling, redness, warmth, and pain in the affected limb. The patient's decreased mobility and potential for skin breakdown increase the risk of cellulitis.

Pulmonary Embolism (PE) source: Although not directly causing the swollen foot, a DVT could lead to a PE, which is life-threatening. It's crucial to consider this possibility, especially if the patient shows signs of respiratory distress or sudden onset of symptoms.
Septic thrombophlebitis: This is an infection of the venous system, which could be life-threatening if not promptly treated. It might present similarly to DVT or cellulitis but requires urgent antibiotic therapy.

Lymphedema: This could be a consideration if the patient has a history of lymph node removal or radiation therapy affecting the lymphatic system. However, it's less likely in this scenario without such a history.
Compartment syndrome: This is a condition where increased pressure within a muscle compartment leads to muscle and nerve damage. It's rare but could be considered if the patient presents with severe pain out of proportion to the swelling, pallor, poikilothermia, paresthesia, and pulselessness.