[Dixielandjazz] Need help with song: "Im Leavin' This Morning"

[Craig I. Johnson]

I have a copy of the trumpet part to the Sonnanstine-Wetterau arrangement
of the song "I'm Leavin' This Morning." I have 2 issues with it and can find
nothing on the Internet except links to this arrangement at "YEstertunes"
My questions are:
Who is the composer of this tune? No attribution on the trumpet sheet.
      The only thing I can find with and internet search of the title is that
      it was a major part of the Robert Johnson song "Rambin' on My Mind'
Secondly, the melody in the "B" part is not complete in the trumpet part.
Can anyone contribute to the exposition of this part?

Thanks,
Craig Johnson
Cornet - The Maine Street Paraders