Jarod is a 35 year old man who has noticed his swallowing gradually worsening over the last 5 months. He admits that the problem is intermittent and that it is noticeably worse for solids compared to swallowing liquids. His weight is stable and he denies any abdominal pain or reflux.
Past medical history includes Asthma but he is otherwise fit and well and on no regular medication.
What is the most likely diagnosis?