My 18 Year Old Daughter Has A History Of Guillian-Barre

My 18 year old daughter has a history of Guillian-Barre at age 9 and Rocky Mt Spotted Fever positive at age 5, and over the last year has started having symptoms of fluctuating heart rate (constant), extreme fatigue (daily), with episodic dizziness and short of breath. Her heart rate will drop to as low as 42 and then shoot up to as high as 160 in just a matter of seconds/minutes and has no consistency to her rate at all. She is currently on metoprolol which is lowering her BP but doing nothing for her heart rate control. Her resting rate at night is typically 120-130 when checked with some drops and spikes as well.