In an earlier post, I described my experience with a frozen shoulder. Here are some pictures showing exactly how I rehabilitated myself and how I recommend my patients stretch on a daily basis.
The initial position will look something like this. I am using a jar of sauce to provide some downward pressure. My good arm is placed in a similar position and allowed to rest with the shoulder, elbow, and wrist touching the floor. When your bad shoulder is hurting from the stretch, look over at your good shoulder and remind yourself what normal range of motion looks like.
This is the goal. Now I am able to touch my shoulder, elbow, and wrist to the floor at the same time.
You will not get to this point quickly. It will likely take hours of stretching like this over weeks to go from the first picture to this one.
Here is how it looks from above.
Gradually bringing your hand and elbow closer to your head will add additional stretch.
Some key points:
Orthopedic Surgeon focused on the entire patient, not just a single joint.