Hi,
It may occur in viral fever also, but since you have fever is for 8 days it needs to be investigated in detail.
If you can share her reports and details about her clinical history, may guide you accordingly.
Few investigations which should be done are blood culture, urine routine microscopy and culture, widal test, malaria antigen test,
complete blood count,
liver and renal function test.
Best wishes for her quick recovery.