Lung damage or abscess. Damage same?

My son on formula milk from birth he got pneumonia 10days after birth I think he is aspirating crackling sounds sometimes is there fluid filled or blockage in lungs he sometimes breath fast and nose problem also he do like something stuck in his mouth...when Pediatric check him he was normal he sometimes produces crackling sounds I want to know is chest congestion and lung damage same ?his chest seems OK when general physician checks him can lung damage or abscess occurs without chest congestion he is two mon ths old only he breathes fast after feeding ..but normally he is playful.. Take feeds but not like other children ...i want to know about lung damage what it is actually