Suggest Treatment For Swollen And Painful Knee

For the last 7 to 8 weeks my left leg from the knee down has become very swollen. It has changed color, it is quite red. It is sore to the touch and of course difficult to wear a shoe. I have been to my doctor twice with this and have had an ultra sound done but they only covered my leg from the knee down and not above it. This showed nothing. I then had a pubic scan done which showed nothing. It seems to be getting worse and my husband and I wondered why they didn't check the entire leg. Now I am getting scared as it doesn't go down completly at night. I get up and it is so sore and there is a large indentation on the front of my leg just under the knee. Is there something that we are missing here? thank you so much. Lillian Wawzonek