Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concern... As per your complain and presentation of symptoms the most probable cause of phlegm in throat, feeling of lump , excessive salivation and a grey coating on tongue are all due to Gastro-oesophageal Reflux Disease or Acid Reflux. This causes reflux of acid and at times food debris from the stomach to throat as well as mouth leading to irritation in throat, mucous formation and excessive salivation.. The grey coating is due to accumulation of food debris over the tongue and due to inappropriate cleaning and hygiene there is coating over tongue.. Youshould consult a Gastroenerologist in this regard and get evaluated and if required he will advise you to get an Endoscopy done.. Medications that can be advised are antacids and Proton pump inhibitors like Pantoprazole, Omeprazole etc.. Drink plenty of cold water.. Take more of Probiotics like Yoghurt. Avoid acidic foods.. Always take a short walk after meals.. Sleep with you head slightly at a higher position as compared to legs.. Clean your tongue using a tongue scraper for removing debris and bacteria.. Hope this information helps.. Thanks and regards.. Dr.Honey Nandwani Arora.