Well it really depends on the injury. On my injury my PT, which is 3 times a week, goes like this:
8 Minute warm up on hand bicycle
Wall Push Ups
Standing medicine ball circles on a wall
Corner lifts (your back in a corner put your arms on the two walls, use the back of your upper arms to lift you off the wall, the farther our your feet the harder it is)
Then 45 degree arm lifts to shoulder height with weight
Then lie on a table face down, your arms and head hanging over side and do the arm lifts again.
Medicine ball walks and pushups. Your stomach on the ball, walk outwith your hands as far as your strength will allow, push up, walk back. x20
Stretches, then ice for 10 minutes.
That's what it looks like. I also have "homework" I do at home which consists of static exercises against a doorway and other arm movements.
If the doctor gave you the stretches do them. He may think it is mild enough. Maybe a just a strain that rest and stretches can work.
But most strains, as long as you rest it after it happens (if you let it rest a year ago) normally goes away after a couple weeks of rest and some physical therapy. But being this is going on year it probably never healed or never healed properly.
Many weightlifters forget all the little stabalizer muscles and joints that actually take a lot of the brunt in weightlifting, like the rotator cuff. That's why a lot of carrer lifters have shoulder problems because they never strengthen the "inside muscles" just the muscles that make you look big.
As I said, take some rest and do the stretches. Rest for a week see how you feel. Lift a little after that, not very heavy, and see if it still annoys you. If it does I would get into a sports therapist.
I'm not in this world to live up to your expectations and you're not in this world to live up to mine. ~Bruce Lee