Hi.
Thanks for your query.
Noted the history and understood your concerns.
Such a weakness that your friend is getting fatigued even on talking or walking indicates severe weakness and hence the cause of this and
nausea has to be found out in spite that she has been sent back home.
I would advise her the following in such a situation:
Get back to the ER or the nearby hospital as is the system.
Insist for proper clinical evaluation, examination and investigations of blood in details like CBC, liver,
thyroid, kidney function, serum electrolytes, Widal for
typhoid and so on.
X-ray of the chest.
Ultrasonography of abdomen.
Tests of stool and urine to complete the set.
This will help to know the exact cause and since medicine is an evidence based science, this will give a proper plan of management.
Till then give your friend plenty of liquids, electrolyte solution, ask to take
bed rest and medications as would be advised by the Doctor.