YOU SAID:

We thought we hit rock bottom, and then we heard a knock from below.

INTO JAPANESE

どん底に落ちたと思ったら、下からノックの音が聞こえた。

BACK INTO ENGLISH

When I thought I had hit rock bottom, I heard a knocking sound from below.

INTO JAPANESE

どん底に落ちたと思ったら、下からコンコンと音がした。

BACK INTO ENGLISH

Just as I thought I had hit rock bottom, I heard a clanging sound coming from below.

INTO JAPANESE

どん底に落ちたと思ったその時、下からガタガタと音がした。

BACK INTO ENGLISH

Just when I thought I had hit rock bottom, I heard a rattling sound coming from below.

INTO JAPANESE

どん底に落ちたと思ったら、下からガタガタ音がした。

BACK INTO ENGLISH

Just when I thought I had hit rock bottom, I heard a rattling sound coming from below.