** 1. since swelling is mainly in the thigh region thus DVT is in the iliac vein, and since there are mainly 3 reason for getting DVT i.e. Hypercoagubility [for which coumadin is given], Injury [repeated stress/strain], stasis [immobility] thus you and your doctor have to narrow the differential diagnosis within these three possible causes. 2. you should consult your vascular surgeon regarding: i. Ultrasound & CT scan:for any abdominal tumor [mainly cancer of pancreas; secondary cause] ii. since chronicity may not cause symptoms early on but if the clot gets dislodged it may travel to the lung causing pulmonary embolism [breathlessness, hemoptysis, pleuritic pain], thus you should be aware of the said signs. PS. To help prevent clots, avoid long periods of immobility,elevate your legs above your heart level, wear compression stockings, and drink plenty of fluids.