Off and on for more than a year now, Lyn will complain about her head. There are times when she's described it like ants on her scalp. Sometimes, she's described it as "tender hard spot." Mom always checks and there's nothing there. The doctor has checked and there's nothing obvious. What seems to help is having her hair brushed. It soothes the unhappy nerves and calms whatever it causing her discomfort.
For a long time, I've wondered it the cause is actually pain or a strong itch. An itch happens along the same neural pathways as pain. While they are different, they are related but respond differently to stimuli. She could be experiencing pain and is unable to help more clearly identify it. It could also be a minor issue but because of her Alzheimer's she may be more focused on what she's feeling, less able to evaluate and dismiss it.
It is happening less these days but when it does, the brushing is the solution; for now at least.