Seeing a specialist is probably a good idea. I had something similar, long ago, and I went to the doc-in-the-box. After unnecessary surgery for the wrong diagnosis, and months of testing, it turned out that a nerve in my wrist had died, but by then it was far too late to do anything about it. By then, the muscles that controlled my thumb had atrophied to the point that they couldn't even be detected any more. In retrospect, it probably had something to do with repetitive use of stiff hemostats at work and/or insufficient decompression during a winter dive.
BTW: I've apparently always had generally poor circulation in my arms - I get that pins & needles feeling every night in bed - and taking a blood sample? Forget about it. When I started taking arginine supplements, all of that finally went away. I even started building up a little bicep mass.