What Causes Red Rash On Lower Legs?

For the past month I have been having this splotchy red rash on my lower legs starting above the ankle not going higher than the knee it is swollen and very painful the pain goes away when I elevate my legs for a couple of days but the splotchy red rash is still there but lighter and my skin looks permanently scarred from this ordeal. I have done some research and my findings are coming to severe blood clots to leukemia.