My Mom Became Ill On Christmas Eve With Fever Chills

My mom became ill on Christmas Eve with fever chills and a rash , after seeing her MD twice she began to get much worse to the point of running very high fever 102/103 and severe leg pain . She was admitted to the hospital ( a very small back woods one because she lives in the country) and has been on antibiotics and diauldid IV for 3 days , with not much improvement . She is not coherent and is still in a lot of pain and has swollen lymph nodes . They can not find a diagnosis.... she has had a very bad case of the shingles 5 years ago but they did test and ruled that out . They are running circles trying to figure out what is wrong!!!?? Please help