What Causes Sore Throat, Pain In Joints And Headaches Despite Taking Antibiotics?

I have a mild sore throat, aching joints, slight headache. I have seen a doctor who prescribed me antibiotics, as I have had tonsillitis before. These are not working, and my throat doesn't feel as bad as tonsillitis. I have been on antibiotics for about 4 days. I have had these symptoms for about 3 weeks, and it is getting worse