Final answer:
Diffuse and episodic pain altered by changed position can be explained by referred pain, where strong visceral sensations are felt in unexpected places. For example, pain from the heart may be felt in the left shoulder and arm.
Step-by-step explanation:
Diffuse and episodic initial pain that is altered by changed position can be explained by the phenomenon of referred pain. Referred pain is when strong visceral sensations are felt in unexpected places due to the misinterpretation of sensations by the brain. Depending on the organ system affected, the pain can be felt in different areas of the body. For example, strong visceral sensations of the heart can be felt as pain in the left shoulder and left arm.