Let me ask you some questions:
How long has this been going on?
Does your finger change colors?
Does is hurt worse at night?
Are you having wrist pain with it?
Thanks for answering my questions.
You appear to have early carpal tunnel syndrome where the nerve at your wrist becomes compressed. You could try wearing a brace for your wrist that will help the nerve to "rest" allowing it to heal.
ALso if you are able to tolerate anti- inflammatory like ibuprofen or aleeve that may help the inflammation around the nerve causing the numbness.
Remote possibility is that it could be a pinched nerve at your elbow or neck.