I had pain in my left side and based on x-ray was diagnosed with lower left lobe pneumonia. taking zpack but not feeling better. any thoughts?

Upgrade in treatment: Well if you have pneumonia, it's very helpful to know the exact cause. This would require going back to the original doctor or seeking a second opinion. A Z-pack or azithromycin is pretty good at treating pneumonia, but could have up to a 25% failure rate based on the organism causing it and your local epidemiology. I recommend proper cultures and lab tests - then an overhaul of your antibiotics.