If all medical explanations have been ruled out as the reason behind her health then the most likely diagnosis is a psychosomatic one which means her mental state is causing physical symptoms to appear that resemble medical ailments. This woman is bereaving the loss of her husband, she feels some sense of guilt as to how she has lived her life, she is depressed and most likely lonely. Psychologically she is not well and what she needs is intense mental health support. Once she feels better psychologically her physical issues should start to improve.