I have a similar situation. My left pinky and half of that ring finger have been 'asleep' for three weeks now. I too can make a fist, but can't do simple things like zip up my jacket. My armpit isn't getting the numbness like you, just those two fingers and side of hand. I'm sorry I don't have answer for you. Just thought I'd relate my problem in case you get an answer-maybe you'd pass along. A lot of people have told me it's a pinched nerve, but don't tell me how to cure it.