YOU SAID:

I must've washed my hands in a muddy stream.

INTO JAPANESE

泥だらけの小川で手を洗ったに違いない。

BACK INTO ENGLISH

I must have washed my hands in a muddy creek.

INTO JAPANESE

泥だらけの小川で手を洗ったに違いない。

BACK INTO ENGLISH

I must have washed my hands in a muddy creek.