Sounds like it could be “intermittent venous TOS,” which is sometimes referred to as McCleery Syndrome. The definitive diagnostic test is a dynamic/positional venogram.

Here is some info:
http://www.ncbi.nlm.nih.gov/pubmed/24334914
http://www.sciencedirect.com/science...41521404016891
http://surgerydept.wustl.edu/TOS_Patients_Venous.aspx

From the WUSTL website shown above:
….In contrast to the effort thrombosis syndrome, some patients with venous TOS may have a more protracted history of arm swelling, fatigue, heaviness, and pain that occurs only on an intermittent basis, especially following vigorous use of the arm. Such patients may have non-thrombotic positional obstruction of the subclavian vein at the level of the first rib, which has not yet evolved to produce axillary-subclavian vein thrombosis.