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With information you have given sudden occurence of body pain
and decreased urinary out put and increased WBC count indicate infection may be in Urinary Tract
or Blood which we call septicemia
and it may cause acute kidney failure.
Giving adequate fluid and emperical antibiotic is correct line of treatment and once Nephrologist
guides treatment/investigation may be done as she is in hospital.
If she responds well to treatment it is well and good but if her renal function indicated by Blood urea and Cratinine level and serum potassium level and Kidney Ultrasonography
,may be that requires dialysis and hopefully she should imporove in few days time.