Its hard to say exactly what is going on, but if the problem is muscular you may want to try re-evaluating your program to see if you are creating muscle imbalances. Below is a section of the great Eric Cresseys shoulder savers article. I also agree with chriscarini on the sports massage. Find yourself a good massage therapist and they will be able to go and feel around and tell you exactly which muscles are tight and irritated. Often times good ones will give you specific muscle stretch/strength exercises to help balance out the length tension relationships. Also, I know you don’t want to hear this but laying off of the heavy weights until you recover.
Good luck.
Shoulder Saver #5: Structural Balance in Training
There’s been a lot of talk of balancing horizontal pushing (e.g. bench pressing) with horizontal pulling (e.g. rowing), and vertical pushing (e.g. overhead pressing) with vertical pulling (e.g. chinning). For the most part, this system works pretty well.
Unfortunately, there are a lot of exceptions to these rules, and often times, people walk away more confused after hearing this than they were before the issue came up. With that in mind, I’ve come to the conclusion that about the only thing you can do is make a list of all the exercises that come to mind, and show how they “balance each other out.”
I look for balance in three main pairs of antagonist movement patterns: scapular retraction vs. protraction, scapular depression vs. elevation, and humeral external rotation vs. internal rotation. In the balancing equation, absolute loading isn’t nearly as important as total reps.
Scapular Retraction
Scapular Protraction
All Rowing*
All Bench Pressing
Rear Delt Fly**
All Flyes
Prone Trap Raise Variations***
Dips
Face Pulls
*Excluding Upright Rows
**Also involves horizontal abduction and external rotation
***Counts as scapular depression, too
Scapular Depression
Scapular Elevation
Scapular Wall Slides
Shrugs
Prone Trap Raise Variations
Upright Rows*
Behind-the-Neck Band Pulldowns
Cleans and Snatches
Prone Cobras to 10&2 (held for time)
Seated DB Cleans
Straight-Arm Lat Pulldowns (strict!)
Cuban Presses
*You’ll find out how I really feel about upright rows in Part II.
Behind-the-Neck Band Pulldowns
Humeral External Rotation
Humeral Internal Rotation
All External Rotation Variations
Bench Pressing, Pushups
Seated DB Cleans
Pullups/Pulldowns
Cuban Presses
Front Raises
Rear Delt Flyes
Dips
Prone Trap Raises
Overhead Pressing
Prone Cobras (held for time)
All Internal Rotation Variations
Now, I’ve deliberately set these charts up so that you’ll realize that the exercises in all left-hand columns are the ones most lifters tend to overlook altogether. If your posture isn’t looking so hot, and your shoulders are bugging you, chances are that you need to shift to the left for a while until you’ve balanced out.