It is likely the AC joint was damaged here due to the nature of the MOI; Cross body loading with the cross. Loads the AC nicely. Pain on the AC joint itself is a good give away in these cases. I'd ask: If this shoulder was bothering her before, during (on a particular hit) or after the session to gain an insight as to whether this issue is fatigue/endurance based, or acute traumatic force based. Id ask her to point to the painful point. If she felt a pop, or crack sensation at the moment of pain What movements aggravate it? I'd assess with Resisted Horizontal adduction Palpation over the AC joint itself Look for a step deformity in the AC Resisted abduction Resisted abduction in the scapular plane. If scapular plane doesn't hurt but abduction does, id rule out supraspin Empty can full can test. Look to see if full can is painful or not. If it is, could mean more rotator cuff involvement. If pain improves with full can or palms up, i'd think more AC