For you I would be looking at Thoracic Outlet Syndrome being that you are I assume under 35 and male. Just from those two datapoints (age and gender) and the fa

For you I would be looking at Thoracic Outlet Syndrome being that you are I assume under 35 and male. Just from those two datapoints (age and gender) and the fact that your symptoms seem to be nerve-related rather than tendon-related... sounds like nerve impingement between the spine and arm. I would read up on the symptoms of Thoracic Outlet Syndrome (and related/sub-syndromes like Pec Minor Syndrome, which is sometimes considered an entirely separate condition and other times considered a sub-type of TOS). There are tests you can do at home (some require another person) to test for all of these, and I suspect at least one will aggravate your symptoms: - Carpal Tunnel Syndrome - Cubital Tunnel Syndrome - Pronator Teres Syndrome - Thoracic Outlet Syndrome - Arthritis (it's probably not this) - Cervical Radiculopathy (it's probably not this, unless you are old or recently experienced trauma in that area, like a car accident) All of these are TREATABLE, especially the first four. Ideally you don't have one of the last two, but both of those seem to typically be an "advanced age" thing. Statistically speaking, you probably have one of the first four. It is theoretically possible to have more than one of these things, but probably very unlikely (I don't have any stats handy, but I know it's uncommon).