Hi just another note the news was having a special that house calls by doctors are becoming popular again. Not sure where you live but it is definelty worth looking into. I agree with above poster about congestive heart failure.
Sorry to hear about your mom...sounds like a tough situation and my heart goes out to you. Swelling in the lower legs can be a sign of congestive heart failure, among other things. I have no idea what to do about her unwillingness to see a doctor. She needs to keep her feet elevated as much as possible (especially while sleeping) to help the fluid move. If her feet/ankles stay swollen for too long, or are very swollen, it can damage the tissues and nerves. I hope she is able to get some help soon. Maybe there's an organization in your city that helps the elderly in cases such as this.
So sorry to hear about your mom. Especially at that age and you trying to take care of them. Swollen feet can occur from many things. She doesnt eat so I am not sure if too much sodium is her cause. When someone has heart or other organ problems or high blood pressure to much sodium cause swellin especially with heart problems. Sice your mom wont go to the doctor is it a possiblity to get a visiting nurse (actual nurse not nurses aid) there are companies out there that send qualified register nurses to homes to check on patinets. Maybe its a possiblity to look into this. If I recall one tv commercial for Bayada nurses (not sure if that was spelled right) maybe you can research the number call them and see if a nusre can so how come to your moms home and look at her that way. Wish you well for your mom