Final answer:
Sudden, severe pain should be reported immediately as it may indicate serious health problems requiring urgent care.
Step-by-step explanation:
If someone complains of sudden, severe pain, this should be reported at once. Sudden, severe pain can be an indicator of serious medical issues such as heart attack, appendicitis, or other emergencies. Healthcare providers need to promptly assess and address any new, intense pain to prevent complications. While the other options listed (a bowel movement, disliking food, and stiff joints) are noteworthy, they don't generally require immediate intervention like sudden, severe pain does.