The weights not the issue, I usually do pullups with palms facing away & arms about shoulder width apart. Then I read somewhere that to really isolate the lats use a wider grip, so I did and after a few reps my left shoulder felt really loose and clunky. So I did a bit of research and apparently chin ups with arms that wide are terrible for your rotator cuff. I think the idea of that wide grip is to do behind the head pull ups.
if its 'loose or clunky' that could indicate shoulder instability.. you may have some kinds of knots in your shoulder that can cause the muscle/s to weaken, hence your shoulder may hurt. To work these knots, you need to do some kind of myofascial release i.e massage.
If it is terrible for the rotator cuff then don't do it
just my 2c worth, from reading all about trigger points and muscle instability....