It occurred to me that, if you are left handed in everything but playing the guitar, you could maybe experiment with playing the guitar the left handed way, which would mean you'd be using your right hand to hold down the chords and so forth.

And the other thing would be trying playing with open tunings.

That's over and above getting advice from someone who really knows about musician's injuries, who'd very likely be a physiotherapist or something like that rather than a doctor as such.