I think I know what the issue is and what needs to be done. Based on symptoms and location, I either have a winged acromion (part of the scapula that comes to the clavicle) or a bone spur that binds in the bottom of the bench press. Best guess is that surgery is required and I'll have 3-4 months of recovery time. Either way this is better than continuing to try and work around it, making no progress, and then having 3-4 months of recovery/rebuilding to do another 6 months down the road Most people don't understand that lifting is about Stress, Recovery, and Adaptation (SRA). The goal with training is to Stress the body such that homeostasis is disrupted. This Stress must be sufficient enough to disrupt homeostasis, but small enough that the body can Recover and Adapt such that the baseline is moved slightly upward. The goal of training is to STIMULATE, not annihilate. Doing more volume than necessary to never get past early intermediate levels of strength. Although this video is about SRA and powerlifting, but the basics of the lecture apply to ALL training.
As for the combo of heavy and light weights, you seem to have it about right based on the accumulated fatigue from the heavy sets proceeding the lighter work. I'm going to get it checked out soon. For now, I'm going to avoid doing things that make it hurt which are mostly bench and press. Chinups, laterals, and rows don't bother the shoulder at all. If you aren't running AAS, strength work is VERY important for getting bigger. Sets of 5 do a half decent job of putting on size while building tons of strength. Interestingly, from a muscle physiology perspective, if you want to get bigger the optimum weight ranges ranges for size are 5-7RM and 10-12RM working very close to failure (to recruit the largest MU's based on the size principle.) tl;dr: If you want to get bigger and aren't on gear, training with a pretty even mix of sets of 3-5 and 10-12 is going to yeild some sweet results provided you (1) work really hard and push yourself, (2) have a plan for adding weight to the bar over time, and (3) eat enough.