Hi there,
Thanks for your query.
More information is required in order to pinpoint the cause. 
However, the brief symptoms, particularly 
shortness of breath at night (?while lying down/sleeping) is strongly suggestive of impending Left 
Heart Failure, which is also responsible for all other problems.
She requires urgent consultation with a Cardiologist (it is an emergency), who will evaluate her, get ECG, Chest X-ray, 
stress Echo done and prescribe appropriate medical treatment.
Consult your doctor/Cardiologist at the earliest, and apprise him of my opinion. I am certain that he will agree with me.
If you find my response helpful and informative, do not forget an “excellent” (5-star rating)  to my answer, to ENCOURAGE ALL doctors- engaged in social service- to render sound advice to the FREE queries. 
Take care
Dr. Rakesh Karanwal