The Daily Mail reports that Emma Mapp experiences a dull ache in the centre of her left shoulder that worsens to the point she cannot raise her arm. She initially attributes the pain to a possible muscle strain from working out at the gym. According to the article, a medical diagnosis follows the progression of symptoms, with the condition described as relatively little-known. The report presents the diagnosis and identifies what it says is the “surprising cause” behind the shoulder pain. Beyond the account of the symptoms worsening from mild discomfort to significant loss of arm movement, the coverage focuses on the personal narrative and the eventual clinical explanation. The available information emphasizes the change in severity and the resulting inability to lift the arm, as well as the transition from a self-assumed muscular injury to a formal diagnosis. The piece does not provide additional context in the excerpt about treatment, timing, or broader prevalence, and further details about the condition and cause are not included in the supplied text.