We present a case of a 53-yr-old woman presenting with insidious shoulder pain and weakness. This case will go through the physical examination of the shoulder, a broad differential diagnosis, and analysis of appropriate imaging and tests to culminate in determining the final diagnosis. The objective of this clinical vignette was to highlight the importance of obtaining an extensive differential for shoulder pain and give readers a chance to critically analyze the case findings through electromyography interpretation, evaluating neurological signs and identifying key points in history taking. In addition, readers will also learn the evidence behind the available treatment options.