I’ve asked questions here before recently about her situation. She’s 87 with early stage dementia. She’s lost a lot of weight. Doesn’t want to eat. Very frail now. I think she’s upset about not living in her home now and is upset with my brother and me for moving her to a facility since she requires skilled nursing for now. She’ll never be able to live at home again. Breaks my heart. She seems miserable. I think she’s given up. I don’t know how to give her hope. I’ve felt, for the last few months, that she’s losing interest in everything.
Was the injury recent?
If so she may be "reliving" the incident that caused the injury that may be why she is "protecting" her head.
Check out her facial expression when she is putting her head in her hands or as she is covering her head. Do her facial expressions indicate pain. Not her words but the way she looks. Think of the pain scale they use at the hospital from a smiley face to the grimace face. There are non verbal cues to check for pain when someone does not know how to express verbally.
Is she in a bright room when she does this? It might be possible that bright light bothers her. Either natural sunlight or fluorescent lighting. This may be a result of the head injury or it could be a visual thing.
Is she is a room full of people when she does this? If so it might be that lots of noise, people are confusing to her. Try a quiet area where there is little else going on so she can concentrate on just you.