What Causes Swelling In Left Leg At Calf, Ankle And Foot?

Dear doctor,

There is a swelling only in left leg below knee at calf and anke and foot since 3 months.It is a pitted swelling as when pressed with finger it stays for some time. Doppler was done and report says no clots can be found. An epithelial edema ( fluid accumulation ) can be found in calf. CT scan with contrast of liver, kidney, abdomen all shows normal. ECG shows heart as normal. All blood analysis says renal functions as normal. Its 3 months now and still swelling has not reduced and pain is intermittent. No reason could be deduced and no treatmet can be found. Could you advice what other test can pin point the result as im worried about her since if there is any clot and if it breaks and moves it may be dangerous. So kindly request your advice on what can be a reason or what other tests can be able to find the reason. Or what kind of specialist to be consulted.