Respected User, hi I evaluated your query very thoroughly.
*This relates to underlying pathological process going in her blood due to 
  some bacteria / virus infecting through any route of the body as evidenced
  by narration of back ache, 
chills , weakness, 
nausea , head ache.
*In our clinic after thorough clinical assessment of the patient , recommend 
  certain Laboratory parameters as - CBC , 
ESR , Peripheral Smear - Fasting 
  Blood Sugar - S.
Widal , S.electrolytes , Urine analysis & decide final line of
  management after perfect diagnosis .
*Till that we recommend :
@ Have as much liquids as possible preferably boiled water, coconut water,
    green tea, coffee, home made juices, butter milk .
@ Have light diet , avoid oily / spicy / nonveg stuffs / beverages.
@ Avoid 
stress / 
anxiety.
@ Keep ambulatory not bed ridden.
@ Avoid 
smoking / alcohol / any abuse substances.
@ Maintain her BP , weight chart.
@ Antacids with analgesics help for temporary time till diagnosis is awaited.
 Hope this clears your query.
 Thanks for using Health Care Magic & reviewing my answer carefully.
 Wishing her fast and speedy recovery from the same.
 Regards.
 Bye dear take care of her.