What’s wrong with my little sister? She’s 11 years old

Patient: What’s wrong with my little sister? She’s 11 years old. She’s a dancer so she’s relatively active. For the past two weeks she’s had a fever that never goes under 100°F. My mother took her to the ER on the 4th day of her fever being present. The ER doctors said enzymes in her liver that pointed to Hepatitis A. They sent her home with a fever still. The following day she was taken to her pediatrician who prescribed her meds and advice to stay on a low protein, high sugar/carb diet. The next day we took her back to her pediatrician with a 104° fever. The doctor said my sister had Hepatitis A, Mononucleosis and a UTI. The doctor admits her to the hospital. On her 3rd day in the hospital she was told that the hepatitis test was negative, what she had was salmonella. Today, her 5th day in the hospital, the doctor tells us she was negative for Salmonella. They ran a CT scan to see if anything else showed up. They said her spleen was a little enlarged but everything else was normal. Her fever continues to to as high as 103° then back down to 100° with ibuprofen. The doctor said they’d keep her in a hospital a couple more days to see if anything changes. My mom is terrified because she doesn’t know what else this could possibly be. Can someone please help with some advice or ideas on what could possibly be causing her fevers! 🙁

Doctor: