YOU SAID:
He is a pain in the but
INTO JAPANESE
彼は痛みであるが、
BACK INTO ENGLISH
He is in pain,
INTO JAPANESE
彼は痛みを感じている
BACK INTO ENGLISH
He is in pain
INTO JAPANESE
彼は苦しんでいる
BACK INTO ENGLISH
He is suffering.
INTO JAPANESE
彼は苦しんでいる。
BACK INTO ENGLISH
He is suffering.
That didn't even make that much sense in English.