It's gotta be bad form or shoulder placement man. You're not letting your shoulders slump when you do them right? Once I stopped that my collarbone stopped hurting. Once I stopped putting my arms so far behind me, it stopped feeling my joint was gonna rip in half. I know you know how the movement is supposed to work. But have someone watch you. If anything but your arms are bending you might be doing it wrong. I thought the pain was just a thing associated with dips I'd grow out of, till a dude downrange was like "hey man I see you in there all the time and you hold your shoulders after dips. Here's 2 things you're doing wrong." I've been golden ever since.