Luckily in my case, it came on gradually and I took some preventive action which solved my problem completely. (There was a point when I was taking Naproxen 5x per day and using Icy Hot after every workout to dull the pain so I could sleep.) I knew it would not get any better, so I did a little research and found some good info.

When you stand with your arms extended to the side (paralell to ground) and rotate/twist arms forward, this is internal rotation. Rotate/twist arms backward...this is external rotation. From what I understand, most of the pressing motions strengthen internal rotation muscles. Very few excercises strengthen the external rotation muscles.

As you get stronger, your shoulder joint gets out of balance. You then start putting more stress (more weight in bench, etc) on a joint which is out of equilibrium. Injury then follows.

What I started doing was specific excercises to strengthen EXTERNAL rotation muscles. The best I came up with mimics the effect of the "Shoulder Horn" (a rotator cuff training aid). I stand by the squat rack and adjust the resting bar height so that it sits about armpit height. I rest my upper arm on the bar, with bar end in armpit. Use a !LIGHT! DB. 90 degree bend in elbow with forearm parallel to ground and raise to upright position. Roll your upper arm around the bar in squat rack. Use only rotation muscles, not rear delts. This is very hard, and 10-15# is all that is required. Do 3 sets of 10 twic per week. People may look at you funny, but who cares. It works..

For more info, look up the shoulder horn and mimic the motion, or just buy a shoulder horn.

I started this excercise about 4 weeks ago, and I now have no more shoulder pain. My bench went up too.