I Just Was Diagnosed And Treated (with A Penicillin Shot

I just was diagnosed and treated (with a penicillin shot and steroid shot) with strep throat a week and a half ago. I now have a bad cough, coughing up yellow/brown stuff, runny nose, swollen/red tonsils, and pus on my tonsils. Is it just a cold or was the strep throat not completely treated? Do i need to go back to the doctor?