YOU SAID:

my back hurts really bad and I don't know why

INTO JAPANESE

背中が痛い本当に悪いと私は理由を知らない

BACK INTO ENGLISH

I do not know the reason if my back hurts and it's really bad

INTO JAPANESE

わからない理由私の背中が痛いとそれの本当に悪い場合

BACK INTO ENGLISH

I do not know why my back hurts and it's really bad

INTO JAPANESE

背中がとっても痛むの

BACK INTO ENGLISH

My back hurts really bad.

INTO JAPANESE

背中がとっても痛むの

BACK INTO ENGLISH

My back hurts really bad.