Straighten your shoulders out is the most I can think of. Don’t dangle, but keep yourself in form as your pulling yourself up

5

Shoulder pain during pull ups is a sign of instability. You want to think about keeping the shoulders down and back while you go up. Face down Supermans help w shoulder stability (look the movement up). Squeeze and hold for a sec on each rep.

3

I would say get a wider grip but from the looks of it, it seems thats not an option

1