Audrey is a 69-year-old with a diagnosis of end-stage breast cancer with metastasis to the lung and bone. You have received a call that she is having increased pain. Upon visiting, you find her to be having increased pain in her left lateral chest area, which is sharp upon inspiration, and tender to palpation. She reports having increased coughing during the night, and experienced a sudden, stabbing pain in this area during one of her coughing episodes. She states that it has been painful ever since, especially when she takes a deep breath. What do you suspect may be happening with Audrey?