What Causes Persistent Fever And Redness In Upper Mouth?

I am feeling feverish every evening /night without actually having a fever. I feel cold and feel that my throat upper mouth is red/ raw/sore.This has been going on for about 3/4 weeks. I also had lo grade flu symptoms, for which I took a course of Antibiotics. I have lost about 28 lbs in teh last 5 months and have completely lost my appetite