I was diagnosed with strep 6 days ago. i was given a shot of penicillin& got better but it came back 2 days ago.i'm on 3rd day of z pac with no change

Streptococcus: If no fever, wait. You could need a culture and a doc who does not waste antibiotics on viral inflammation. The fiery red strep throat is infrequent and often the sore throat is viral. Frequent PCN for viral sore throat is not good medicine. If the strep was cultured and positive, I apologize. The fact that the antibiotics made you feel better may be coincidental.