Peripheral Neuropathy: This condition is common in HIV patients, especially those with advanced disease or on certain antiretroviral therapies. The symptoms of leg pain, sleeplessness, and low energy can be attributed to peripheral neuropathy, which causes damage to the peripheral nerves, often resulting in pain, numbness, and weakness in the legs.

Anemia: A common condition in HIV patients due to the disease itself or as a side effect of antiretroviral therapy. Anemia can cause low energy and fatigue, contributing to the patient's symptoms.
Depression: HIV patients are at a higher risk of developing depression, which can manifest as sleeplessness and low energy. The physical symptoms of leg pain could also be exacerbated or perceived as worse due to a depressed mental state.
Musculoskeletal Issues: As a farmer, the patient may be prone to musculoskeletal injuries or conditions such as strains, sprains, or overuse injuries, which could cause leg pain and contribute to sleep disturbances and fatigue.

Osteomyelitis or Septic Arthritis: Although less common, these infections can occur in HIV patients, especially if they have a history of injection drug use or other risk factors for bacteremia. Leg pain could be a symptom of a deeper infection, which would require immediate medical attention.
Lymphoma: HIV patients are at an increased risk of developing lymphomas. While less likely to present with leg pain as the primary symptom, systemic symptoms such as low energy and sleeplessness could be indicative of an underlying malignancy.
Tuberculosis (TB): Given the patient's immunocompromised state, TB is a critical diagnosis not to miss. It can present with a wide range of symptoms, including systemic symptoms like low energy and sleeplessness, and can affect various parts of the body, including the bones and joints, leading to leg pain.

Avascular Necrosis: This condition, which involves the death of bone tissue due to a lack of blood supply, can occur in HIV patients, especially those on long-term corticosteroid therapy. It could present with leg pain and should be considered in the differential diagnosis, although it is less common.
Nutritional Deficiencies: Certain deficiencies, such as vitamin B12 deficiency, can cause neurological symptoms including peripheral neuropathy, which might present with leg pain, and also contribute to low energy and sleep disturbances.