How do i know if i have an infection in my lung?

Pneumonia: Some pneumonias have few symptoms (walking pneumonia) but most common symptoms associate with pneumonia are fever/sweats, feeling tired & weak, cough productive of green or rusty (bloody) sputum, chest pain, pain with taking a deep breath, feeling winded (short of breath). Depending where in the lung the infection is may see back pain, flank pain, nausea, diarrhea, or shoulder pain.