UPDATE: It's old news but to end the story, it turned out to be Paget Van Schroetter Syndrome (upper-extremity,subclavian deep vein thrombosis). It occurs in healthy individuals that perform repeated movements using their arms. It can happen doing overhead presses, pitching a baseball or even waving to a friend.
The guy had to have venous angioplasty done to remove pieces of the fibrous clot and has some of the hardened clot still stuck to his brachial vein.The guy's on anticoagulants for the next six months (at least) with a re-evaluation after that. He can't do any overhead pressing or pulling movements or take AAS. He can do everything else though.
All in all,he's just glad it wasn't AIDS