OK, I Googled "tos" and discovered it is thoracic outlet syndrome. This makes sense to me. I had actually seen it in the Merck Manual before getting nerve conduction tests & had most of the symptoms. However, I mistakenly thought it was related to thoracic *spine*. I asked one of the doctors if there could be problem in thoracic spine (as I have often had pain in that area), but that idea was rejected.
I found this article which describes symptoms of pectoralis minor syndrome:
www.ecentral.com/members/rsanders/ I will pursue this with my doctors. Thanks!