A while back, I had pins and needles in my left ring finger and little fingers. Lasted on and off for days. Very worrying.
Ended up getting checked out by my friendly chiroprator (the man is a miracle worker).
It was a trapped nerve. Very common.
One treatment and I was fully recovered in days.
Apparently, numbness in specific fingers but not others is a clear sign of nerve issues, and you can google easily to discover which particular arm nerves are affected. nerves get pinched in the neck, shoulder, elbow and wrist, and there are 'nerve flossing' exercises (see you tube) which help a lot.
I thought it might be the onset of neuropathy. Profoundly grateful that it wasn't!