Sharyn
I have had persistant shoulder and neck problems which gives me referred pain in the left hand. As well as various treatments I also changed my guitar tunings!

For playing melodies, DADGAD and CGCGCD have scales which fall under your left hand much more naturally than EADGBE. For playing chords, I came up with DGDGAE, which sounds bizarre, but actually lets you make lots of chords with just 2 fingers. There are easy G, C, D, Em, A shapes among others as well as a simple 4 string Dm.

Best of luck with the hand!
KP