Chronic Venous Insufficiency (CVI): This condition is characterized by the veins having problems returning blood from the legs back to the heart due to valve issues. It often presents with bilateral calf pain that worsens after standing for hours, which matches the patient's symptoms. CVI is common in middle-aged individuals and can cause pain without the classical signs of deep vein thrombosis (DVT).

Peripheral Artery Disease (PAD): Although PAD typically presents with intermittent claudication (pain in the legs or arms that occurs during exercise and subsides with rest), some patients may experience pain at rest or after prolonged standing. The absence of stretch pain and classical DVT signs does not rule out PAD entirely.
Musculoskeletal Strain: Prolonged standing can lead to musculoskeletal strain in the calf muscles, especially if the patient has a job that involves standing for long periods or has recently increased physical activity. This could cause bilateral calf pain without specific signs of DVT.
Overuse or Repetitive Strain Injury: Similar to musculoskeletal strain, overuse or repetitive strain injuries could cause calf pain, especially if the patient has recently changed their activity level or started a new exercise routine.

Deep Vein Thrombosis (DVT): Although the patient does not exhibit classical signs of DVT, it is crucial not to miss this diagnosis due to its potential for severe complications, including pulmonary embolism. DVT can sometimes present atypically, especially in patients without typical risk factors.
Popliteal Artery Entrapment Syndrome: This is a condition where the popliteal artery is compressed due to anatomical abnormalities, leading to claudication and potentially severe ischemia. It's less common but critical to diagnose early to prevent serious complications.

Compartment Syndrome: This is a condition where pressure within the muscle compartments increases, leading to pain and potentially serious complications. It is less likely given the description but should be considered if the pain is severe and accompanied by other symptoms like paresthesia or weakness.
Neurogenic Claudication: Caused by spinal stenosis or other neurological conditions affecting the nerves that control the legs, this can lead to pain in the calves after standing or walking. It's less common than other diagnoses but should be considered, especially if there are accompanying neurological symptoms.