John’s mention of ‘Dupuytren’s Contracture’ reminds me that I had that in my right hand about six years ago. I think I got it from carrying my brand new Miraphone 5050 in its hard case about two blocks. That’s when I decided to get a gig bag so I could carry it over my shoulder. Not sure if it was the weight of the M5050 or the hard handle or combination of both. My Dr suggested I just do stretching exercises pushing my fingers against the palm of my other hand. There was a lump in the palm of my right hand or knots of tissue that eventually went away. Thankfully it didn’t affect my playing too much.