What Causes High Fever, Sweating, Sore Throat And Dizziness After Taking Z-Pak?

My boyfriend went to the doctor on Wednesday with a cough and general malaise. He was prescribed a Z-Pak and was given an additional two starter pills. Since then, his fever has spiked to 102 (had 99.2 on Wednesday), is sweating profusely, coughing, sore throat and dizziness. Does this mean he's getting worse? Should we go back to see the doctor in the possibility he may have caught something the Z-Pak can't treat?