I don't recall what key Sonny and Brownie did Trouble In Mind in,but G and A would be the likely male vocal keys.
Here it is in G.The chords ought to be above the words,but online this way works:

Trouble in [G]mind I'm[D7]blue
but I[G]won't be blue al[C]ways[C7]
you know the[G]sun gonna shine
in [D7]my back door some[G]day[G C G D]

Here's a chord chart.The slashes are bar lines.4 beats per bar.On the bars with 2 chords,each chord gets 2 beats.

G / D7 / G / C C7 /
G / D7 / G C / G D /

This chord progression is a great example of an 8-bar blues.If you have any questions,just ask.