Problems in rhomboids are often accompanied by shortening of anterior structures, protracting the scapula and thus overstraining the posterior muscles. You may well find a surprising amount of tenderness and change in pec minor, for example. Hence working the site of the main symptom alone typically gives short term relief followed by worsening. Then we need to understand what other factors cause the anterior shortening. It may mean looking elsewhere in the body, and it may mean educating the patient.