Hi.. Thanks for the query.. As per your complain swelling of the tissues behind the tongue seems to be due to swollen Circumvallate papillae that are large taste buds present at the back one third of tongue and are in a typical V shaped pattern.. They can get inflamed and swollen due to causes like post nasal drip, oral and throat infections, burning with hot fluids and chemicals like concentrated solutions of mouthwash etc.. I would suggest you to consult an Oral Surgeon and get evaluated and get a proper examination done.. As of now he can do warm saline gargles as it will be helpful in both reducing mucous as well as relieving inflammation of the tongue tissues.. Along with it take mucolytics and also do steam inhalation.. Avoid spicy foods as they can increase mucous.. Drink plenty of warm water.. Hope this helps..