Hello, I am a 29-year old female with a low grade fever that I cannot get rid of. My temp has been ranging from 99.3 up to 99.9 for the past five days. My normal temp is around 98.5. The first few days, I had the chills, headache, and felt fatigued. Now the fever is pretty much my only symptom. I went to my PCP yesterday and she said that it must be the flu--my lymph nodes were not swollen and lungs are clear. So she told me to drinks lots of fluids and rest. My question is, what could be the cause of having this for so long?? Should I be concerned, and how long should I wait before putting in another call to my doctor?