For The Past Several Weeks I Have Had Some Swelling

For the past several weeks I have had some swelling in my left foot and ankle. The swelling has now become worse and it hurts to walk or put pressure on this foot. I had a ultrasound done a few weeks ago and it was negative for blood clot. Been referred to a vascular surgeon-how would this person help me? I have stayed off of my foot and the swelling is still there. I cannot get a shoe on it comfortably. Thanks