I had almost the exact same thing happen. In my case it was just a pinched nerve - a ring I had on before going to bed put too much pressure on a nerve at the knuckle and the top of my finger was numb for over a week. I went to the doc and they told me the same thing; EMG or an anti-inflammatory. Not thrilled about the EMG either.
Take ibuprofin for a couple days to minimize any inflammation and you'll notice the numbness will begin to subside. Give it about a week to get 100%. If it doesn't get better, you might wanna consider the EMG, but since you know when it occurred, I'd be willing to bet it's just a little trauma to a nerve.