Will Zpack work for me?

I got diagnosed with Strep throat and a sinus infection on Monday. I was prescribed amoxicillin and after getting worse (about 4 days) I was switched to Zpack. I took my first dose around 2:00pm today. When should I expect to start feeling better? It's about 9:00 now and I feel the same, if not worse. Will it not work well for me cause amoxicillin didn't work? Please answer! I'm in so much pain!