When I was small, I was in the hospital for pneumonia. I was also in a car accident.
「小さいころ、肺炎で入院したことある、あと交通事故も」は英語で:
When I was small, I was in the hospital for pneumonia. I was also in a car accident. といいます。
または、When I was small, I was hospitalized(入院) for pneumonia and was also in a car accident. とも言えます。
Pneumonia が肺炎のことですか、発音はとても難しいです。カタカナにすると「ナモーニャ」です。