Originally Posted by Steven Low
Add some more horizontal pulling strength work, and external rotation strength work (only do side lying external rotations and some cuban presses).
I strongly suspect that your IR/ER imbalance and weak posterior shoulder area are causing your pain. When you jerk if your shoulder isn't balanced, the instability of your muscles to balance the weight right away can cause pain just like any other related imbalances.
Horizontal pulling = rows?
I'll add the side external rotations, cuban presses, and overhead holds and cut out jerks. Should I be looking for a point where my external and internal rotation strength is roughly equal?
Thanks to you, Leo and Derek for the help and advice.