1. Interstitial Lung Disease with high fever and unable to diagnose: could be possible Idiopathic Interstitial Pneumonia
that have no known cause and affect lungs Primarily.
2. blood test
usually don't confirm the diagnosis but are done to search for possible secondary infection. (high WBC count)
3. In hospital, a TEAM of doctors is/are looking after her, so sooner or later they will come up with a Provisional or Final diagnosis.
4. you haven't mentioned about her BP range and neither about the elevated creatinine
5. any h/o of Autoimmune disease
6. presently in hospital antibiotics and corticosteroids
are the main stay of treatment.