What Causes Fatigue Along With Headaches And Memory Loss?

My mom is currently off sick from work as she kept having funny turns where she says she felt like all the energy would drain from her. Afterwards thisi would leave her feeling drained and tired. She also has recently had the sensation like her legs feel like jelly. Other symptoms are shaking all over, headaches and memory loss. She has had full blood tests at her Gp where most have come back clear. She is also awaiting the results of a few blood results. Her Gp has also refered her for a brain scan. Please advise what this could be