A 35 years old gentleman, with no previous medical or surgical background, and is not on any medication with no any known allergy, not a smoker with no alcohol intake, was reffered by his GP due to increasing and intermittent swallowing difficult for both solid food and liquid for the last 3 months. He described as soemtime he felt like the food will stuck at the oesophagus, and will require a lot of effort or drinking a lot of water to get it down. Intermitently, he will have the same problem when drinking water as well. He denied any weight loss, or reduced appetite or epigatrsic pain or reflux symptom. No family history of any significant medical disease. Gastroscopy (OGD) was performed, and macroscopically it was an entirely normal examination. Lower and mid oesophageal random biopsy were taken, and awaiting the histology report. What will be your differential diagnosis ? and What will be the management plan ?