Raynaud's Syndrome or a pinched nerve would be my guess!! I lose feeling in my fingers a lot. I lose feeling in other various parts of my body as well, for multiple different reasons! It never stops being unnerving, but you'll get used to it! The only thing to worry about is if the tissue on your fingers can be pinched and don't snap back. Tell the doc right away if that happens cause, I have been told, that means tissue damage is occurring.