Pain

Pain can be expressed in many ways, not just verbally.
If someone grimaces or is protective of a body part (called guarding) this is a symptom of pain.
Irritability, changes in mood and/or behavior also can indicate pain symptoms.
If you are in pain, do you want to eat? Interact in your usual manner?
If someone shows discomfort when repositioned, they were probably in pain before the repositioning.
Look at the whole person, not just the words they say. Families are often taken aback when pain management (sometimes just Tylenol scheduled at regular times) is started. Some people feel that it is "unnecessary".
But, ask yourself this - is life good when you are in pain, even a low level of it?
No one should deal with constant aches and pains. It is not "just a part of getting older".