My elderly (83yr old) neighbor suffers from swollen legs and her right foot gets fiery red and hot. This usually happens in the evenings when she reclines to watch TV. Her doctors have done all types of tests and say her heart is OK and there isn't a blockage that they have found. She has had a heart attack a couple of years back and is fully recovered. What could be causing the swelling (adema?) and the red hot foot?

Optional Information:
Female , Age: 50