Suggest Remedy For Persistent High Fever And Shivering

Hi, My name is Sharib, My mother is hospitalised after getting fever followed by shivering. Initially doctors tested her for Malaria But negative. WBC count was slightly more than normal, so started antibiotics on the basis that some bactarial infection is present. But it didn't worked. Later on They tested her for Dengue, Chicken gunia but all negative. next direction was towards creatnine and liver tests, and fortunately those were also normal. Now after 4 days, she has started shivering attacks, followed by fever. Please advice what next should we look for. Thanks in Advance.