Odd Shoulder/Scapula Issue

So there is really no pain associated with my condition, but imbalances naturally concern me, and this one is so great I am wondering what it is and how I can remedy it before it becomes a problem.

So any time there is weight put on shoulder, my right scapula shifts disproportionately with my left. I first noticed it when I was doing preacher curls and my right shoulder would drop down WAY further (like at least three inches). If I am using heavy weight I literally CANNOT lift it back up.

I thought it was just a weird thing with preacher curls, but I realized that heavy overhead weight (like calf raises involving shoulder pads or seated military presses on a smith machine) causes my shoulder to depress and my right scapula to stick out as well.

Does anyone have any idea what the problem is/how to fix it? Think it is a mobiliy issue? Nerve innervation issue?