I have worked in construction for 30 years and started lifting at 49 again. been lifting for 2 years and also doing 200 TST every 2 weeks. I, like you have serious issues with my shoulders as I didnt have any to speak of. Now they are one of my best asset. Always warm up the shoulders, before any upper body workout 2 to 3 sets of real light weight (low cable raise, stand sideways to the cable machine with the handle on side and reach across and make a Y where you pull across your chest (only use about 5 lbs ) and go slow. 20 reps 3 sets. Next set the cable handle even with your chest and again reach across your chest and do a side lateral without moving your upper bicep, again light weight same reps. these are great for the shoulder stablizer. What has helped me is the side lateral DB rasises. The big nasty mass builder is the standing shoulder barbell press. I do mine in the squat rack and if you go heavy use a lifting belt. I started out with the bar only (45lbs) and after 10 weeks around 145 lbs, it is brutal be forewarned and dont over do it. Do not be ashamed of just adding 2.5 lbs a week. we are old warriors but were still warriors so do not give up.