I have experienced unexplained swelling to various extremities: the bottoms- the pads-of my right foot and right big toe, my ring finger on left hand, my left thumb and wrist, the top of my right instep. It comes and goes every few days. My feet will be tender/ sore to walk on when symptoms occur. They also itch and burn. Benadryl relieves symptoms for a while, but they return a few days later. Is it a virus? An allergy? What is causing these symptoms?