YOU SAID:
Mom will you wash my back this once?
INTO JAPANESE
お母さん、一度背中を流してくれる?
BACK INTO ENGLISH
Mom, can you wash my back once?
INTO JAPANESE
お母さん、一度背中を流してもらえますか?
BACK INTO ENGLISH
Mom, can you wash my back once?
That didn't even make that much sense in English.