Hi shoulder problem.
The usual form of treatment for this sort of problem is to mobilise and stretch the shoulder.
A small group of Physios work on the principal that the problem is referred pain from, in this case, the spine.
The general name for this approach is the "T4 syndrome".
If the problem is not resolved quickly secondary pain can be palpated in the shoulder and elbow as well as to
the side of the Thoracic spine - T4 is the lateral side of the elbow, C7,T1,2 is the lateral side of the shoulder.
T7,8, is the lateral side of the hand and posterior shoulder, C1,2 is the medial side of the hand, elbow and anterior shoulder,
Also Occipital headaches and some Tinnitus problems.
Treatment to these spinal areas includes mobilisation, posture correction, manipulation, TENS, Ultra Sound.
Heat will give symptomatic relief.
Find a Physio who knows about the T4 syndrome.