What Could Sore Throat With Tonsillitis Suggest?

On Friday I woke up with a sore throat when I looked at the back of my throat I had pus on the right side. I went to the er and they said I have tonsillitis and gave me a shot of penicillin. The next day I felt worse and the other aide of my throat has pus now and is extremely swollen. I took a cotton swab and tried to rub off some of the pus and it feels hard as a rock. When will the penicillin kick in or do I need to be seen again?