I see this is an old post, but I'm sure other people will run across it in the future, as I have. This sounds to me like something I am currently suffering with -- a compression of the nerve that runs from between the C6 and C7 vertebrae. For me this comes from a combination of having a desk job at a computer and over-practicing guitar. In both instances, the culprit is largely bad posture with a face-forward problem (my chin goes forward, so my head is not above my shoulders, which slope forward, causing a strain in the neck and the resulting pinch problem). There are some good exercises on the Internet that can help. Ice and ibuprofen can help reduce the swelling in the nerve (heat can make the problem worse, muscle relaxers will not necessarily help at all). The other possible culprits for you are carpal tunnel and cubital tunnel syndromes. I hope you can get past this, but I do think you'll need to get an instructor that can help make sure you are in the correct posture and are not playing with too much tension/pressure on the fingerboard.