YOU SAID:
Theres something i need to tell you
INTO JAPANESE
あなたに伝えなければならないことがあります
BACK INTO ENGLISH
I have to tell you something
INTO JAPANESE
君に伝えなければいけないことがある
BACK INTO ENGLISH
there's something i need to tell you
INTO JAPANESE
あなたに言わなければならないことがあります
BACK INTO ENGLISH
i have to tell you
INTO JAPANESE
あなたに伝えなければならない
BACK INTO ENGLISH
i have to tell you
That didn't even make that much sense in English.