YOU SAID:

I have a stomachache, so I will take a day off today.

INTO JAPANESE

お腹が痛いので、今日は休みます。

BACK INTO ENGLISH

I have a stomach ache, so I will be absent today.

INTO JAPANESE

お腹が痛いので、今日は欠席します。

BACK INTO ENGLISH

I have a stomach ache, so I will be absent today.