Being a guitar player myself I can understand how painful this disorder may be. Is the last picture of a planet waves finger exerciser?? I have one. If you don't mind then I have a few recommendations. There is a form of yoga called hand mudras that uses hand gestures. You need to be patient and need to practice religiously. Give it a try if you wish.
Please google appropriate symptoms for proper guidance. I am leaving an example video for introduction.
I hope it helps,it has benefited me immensely. Cheers!!
It is a Planet Waves gadget.
There are some bold claims in that video. There are so many alternative therapies that claim a lot and it can be hard to know what to try.
It's basically a gamble and you are in need so there is no way you can verify before trying it for some time. You can read about Reiki too.
I know someone who does reiki, but I'm sceptical about some therapies