YOU SAID:

I have to go diarrhea.

INTO JAPANESE

私は下痢をしなければなりません。

BACK INTO ENGLISH

I have to have diarrhea.

INTO JAPANESE

下痢があります。

BACK INTO ENGLISH

I have diarrhea.

INTO JAPANESE

下痢なんだ

BACK INTO ENGLISH

I have diarrhea.