Marcus is a 45 year old chef with a 4 day history of weakness and paresthesia described in his upper and lower limbs. He has also 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 is keen to recover quickly as he was off work one month ago following Campylobacter gastroenteritis and does not want to take further time off.
What is the most likely diagnosis?