YOU SAID:

My dog pooped in my room where I keep my pizza

INTO JAPANESE

ピザを置いている部屋で犬がうんちをしました

BACK INTO ENGLISH

The dog pooped in the room where the pizza was placed

INTO JAPANESE

ピザが置かれた部屋で犬がうんちをした

BACK INTO ENGLISH

The dog pooped in the room where the pizza was placed