I am not a Dr for sure, but I think this can relate to OA. Unfortunately you playing guitar may increase the pain of your damaged finger. I didn't meet yet one guitar player who wouldn't complain about pain in his/her fingers and even wrists. Same as manicurists have "occupational hazard" and all develop OA in same joints and fingers or hairdressers get carpal tunnel syndrome due to their every day job.
I used to be very active in my gym and did a lot of lifting. I loved what it did to my muscles but I didn't like to feel what it did to my shoulders. Ignorant, I didn't want to go to the Dr to hear from him this is due to my lifting. Finally it got so bad, I couldn't write, forget lifting and had to see shoulder specialist. Yep, the verdict: either you stop lifting and do just cardio or you will need shoulders surgery. I stopped for some time, than it felt better and I started lifting again. We all know how it goes: OK, just a little, not too much.
Long story short: had 2 shoulder surgeries and had to stop lifting for the rest of my life.
I hear you, none of us like to leave something we enjoy doing or doing it all our lives... Very sad, but when we age, everything changes in our body and we have to make choices either have worse problems and pain or make some adjustments.
Wish you the best