Marcus is a 45 year old chef with a 4 day history of weakness and paraesthesia described in his upper and lower limbs. He felt short of breath when out running this morning but is comfortable at rest. Past medical history includes Hypertension which is well controlled on Ramipril. He has recently had Campylobacter gastroenteritis but is in good health otherwise and rarely attends the GP surgery.
What is the most likely diagnosis?