That's where I've got arthritis in the thumb base, after an xray an appointment with an Orthopaedic surgeon then a hand clinic I ended up with splints and cocodamol painkillers...that was 2 years ago. May this year 1 cortisone injection into both thumbs eased the right thumb but not the left one a blether with the Orthopaedic surgeon again didn't recommend surgery as not 100% guarantee to have full dexterity so back to splints again. As for playing I thought a Jazz type neck would be ideal but I struggled with it so out of the blue I tried a Vintera Precission bigger nut width & easier, I guess the thumb isn't curled as such on the back of the neck so happy days. Wish you well bud.