Hello
As you mentioned that she is having "influenza " and all these symptoms are also an indication of influenza.
Abrupt onset of fever , severe myalgia /
arthralgia , severe dry cough(
shortness of breath), loss of appetite , malaise ,
sore throat & rhinitis , as all these symptoms are of "influenza"
She may have influenza.
But the main question is type of influenza , so that proper medicine could be given.
1
Seasonal influenza.
2
Avian influenza.
3 Novel H1 N1 influenza.
Since you mentioned that your sister is a nurse so it is very difficult to say , which type of influenza , she is having .
Tests are performed for detection of type of influenza.
Immunofluorescence test &
Hemagglutination inhibition tests .
So first of all get in these tests so that exact type of influenza can established.
As far she may have blood clot? Your query , it is very difficult to say anything because of short history of illness.
So deal as I mentioned above.