There is enough on the net that explains left heart failure better than my post. It is very hard when you are not the relative in charge. Basically a part of the heart muscle is weakened and this is in the left part of the heart. There are many reasons for this, but the result is an alteration in venous pre-load, which causes the edema and swelling of the legs. The nausea is symptomatic of a heart not getting enough oxygen. The medical profession has a number of treatments available for this condition, so don't give up hope. I only caught bits and pieces from your initial post, but the fact they said "she had a possible heart attack" and your mentioning of "fluid in the legs" is often connected with left heart failure. You could contact adult protective services. Unfortunately, the elderly often are rational enough to refuse supervision of their medical conditions. Dehydration is a common manifestation of this "self-neglect". Try to talk to the "relative-in-charge". Easier said than done.
Thank you for your response. What is left heart failure? Unfortunately, we are not the relative-in-charge and she still thinks she will live alone again. We are very concerned
Symptoms are suggestive of left heart failure. Often treatable. She needs a work-up and treatment, but don't give up hope. Often, unless you are a relative-in-charge or the person being treated medical facilities will decline to provide specifics about treatment or prognosis.