Differential Diagnosis for Lower Limb Swelling, Fever, and Electrolyte Imbalance

Single Most Likely Diagnosis

• Cellulitis or Soft Tissue Infection: Given the acute onset of lower limb swelling and fever, a bacterial infection such as cellulitis is a strong consideration. The history of fever on and off for 15 days suggests a possible chronic or recurrent infection. Ayurvedic medications, while less commonly associated with such infections, could potentially be a contributing factor if they have immunomodulatory effects or if the patient has been using them as a substitute for conventional medical treatment, delaying appropriate antibiotic therapy.

Other Likely Diagnoses

• Deep Vein Thrombosis (DVT): This condition can cause limb swelling and is a common concern in patients with prolonged immobilization or those on certain medications. However, the presence of fever might suggest an infectious or inflammatory component rather than a purely thrombotic event.
• Lymphatic Filariasis: Given the patient's potential exposure to certain regions where filariasis is endemic (especially if the ayurvedic medications were sought as an alternative treatment for symptoms related to such an infection), this parasitic infection could be a consideration, particularly if the swelling is chronic and accompanied by other symptoms like lymphangitis.
• Nephrotic Syndrome: This condition can lead to significant lower limb edema due to hypoalbuminemia. While it doesn't directly explain the fever, infections are a common complication in nephrotic syndrome due to the loss of immunoglobulins in the urine.

Do Not Miss Diagnoses

• Septic Thrombophlebitis: Although less common, this condition is life-threatening and requires prompt diagnosis and treatment. It involves a septic thrombus in a vein and can cause fever, limb swelling, and potentially life-threatening complications if not addressed.
• Osteomyelitis: Chronic infection of the bone can cause localized swelling, fever, and might be associated with the use of alternative treatments that delay appropriate antibiotic therapy.

Rare Diagnoses

• Eosinophilia-Myalgia Syndrome: A rare condition associated with the intake of certain contaminants in dietary supplements or medications, which could potentially include some ayurvedic preparations. It presents with severe muscle pain, eosinophilia, and could have limb swelling as part of its presentation.
• Lipoatrophic Panniculitis: A rare condition that could cause limb swelling, but it's more commonly associated with other specific symptoms like pain and skin changes, and less likely to be directly related to the fever or ayurvedic medication intake.

Each of these diagnoses should be considered in the context of the patient's full clinical picture, including any additional symptoms, physical examination findings, and the results of diagnostic tests such as complete blood counts, blood cultures, electrolyte panels, and imaging studies as appropriate.