Hi,
Her symptoms are suggestive of congestive heart failure and hence will suggest you to consult a cardiologist as she’ll need further investigations like ECG, X-ray chest, echocardiogram etc for the confirmation of the diagnosis and for further treatment. I sincerely hope that helps. Take care.
My mother had similar symptoms, swelling of legs, ankles, and abdomen. She's 74. Also, short of breath, no energy, couldn't get her self off the toilet! When she finally went to the doctor she was told she had heart failure, kidney failure and liver failure. Heart failure and kidney failure can cause the water weight gain in the legs and ankles. The low blood pressure is another sign of distress. If you can, you should get her to the doctor. We have struggled with this since April. She was given weeks to 6 months back then, and she's still fighting, though we can see deterioration. At this age, it's tough because they are frightened about end of life issues. Good luck to you, please try and talk her into getting to the doctor. If she has no other health issues, she could be helped with medications?!