Hi 7 Years Old Girl Is Suffering From Fever 105

Hi 7 years old girl is suffering from fever 105 and 106 from 40 days.her hemoglobin is getting low and now is on 5.5.swelling is on her face n her colour is getting pale.she has pain in bones n her liver has increased in size.we are confused about her disease.now doctor diagnosed it as arthritis.Her all cbc,blood reports,x_rays n ultrasounds r clear.kindly reply me about her disease n treatment.