I am 20 year old female and 120 pounds. I have never had a serious illness, don t have any allergies, or get sick very often. I have had a moderately sore throat for the past few days, a fever, and I now have bloody mucus, which I think is in my sinuses (I am not coughing it up and it hasn t been present in my nasal cavity). I went to the doctor on Monday and he prescribed me with an antibiotic. My fever has persisted for the past five days for the most part. My temperature has not been under 99.5. Tylenol and other similar drugs aren t helping to bring it down very much. Do you think it could be something more serious, and I should go back to the doctor?