Hi all PsychCentralites!

I have a question.

My friends Nanna has been suffering lately from smelling a strange smell.
She complains that it is a very strong and nasty smell.
She can't find the source, and others who come to here house can't smell it.
She convinced that someone is messing with her mind by sneaking around and putting bad smells around her house.
So she's decided to sell the house she's been living in for the past 50years (her late husband built it) to escape the perceived harassment.

Her family are quite upset by it.

She also went for a holiday to her daughters place and noticed that the smell came too. So to some degree she knows that it's in her head, but she's got her mind made up on moving house anyway.

What do you think she has???
Have you ever heard of this type of complaint?

First thought was schizophrenia, but being 80, she's well out of the 25-35 year old onset range.
Then I thought Delirium, but that's more of a confused reality, not a faulty sensory complaint.
Also I think it would be really hard to test for synesthesia, as she's so old and this type of thing hasn't occurred before.

What do you think????