Hello There My Son Was Diagnosed With Pneumonia Today. He

Hello there my son was diagnosed with pneumonia today. He had pneumonia a couple weeks ago and it was treated with amoxicillin but it is back now. They put him on azithromyacin. He is sleeping now, breathing 40 or so breaths per minute with wheezing and sometimes he makes a little half moan like a sick child would do. How do I know when I need to take him in or if he's getting worse?
Thank you.