Sorry, not really enough information. I still say get an anatomy book to see if you can pinpoint more specifically what you suspect.

For example...I have a weird clicking/popping that results in a flare up in the sternal end of my left clavicle. When I turn to the anatomy book I notice that it is connected to the manubrium and sternum by a bunch of ligaments. There is also a ligament between the clavicle and the first rib...ALL stuff around the BP. I suspected some type of subluxation of the clavicle or tiny dislocations and relocations...when I saw the PT, she confirmed that yes, I have a hypermobile left clavicle..and not only on that end but on the other end where it connects with the Acromium a part of the shoulder blade (also referred to as the AC joint). The "movement" can impinge on the BP and other vascular structures...hence the periodic flare ups. But that is me.