I'm not sure if Acupuncture would be helpful for treating your thymus, but
numbness may be treatable.  If you live in Santa Rosa, I'm sure a lot of
Acupuncturists will be in your phone book.  As for references, you may wish to
ask you MD.  Acupuncture has been around longer in California and your
physician may know of someone.

If you can't find someone to refer a practitioner, check your yellow pages.
Ask how long they have been practicing and if they have treated numbness
before.  Avoid anyone who tries to sell you on a package of visits sight unseen
(this goes for any type of practitioner).

If you have insurance, it is likely that it will be covered to some extent.