Your symptoms sound more like a bad case of gastric reflux, either due to acidity or lax esophageal sphincter or due to hiatal hernia (part of stomach forms a hernia into chest cavity). This can cause pain along throat, a feeling of something in the throat, phlegm, and pain in mouth/tongue/throat due to the chemical burn caused by acid from the stomach.
Treatment is a combination of drugs to reduce the acid and lifestyle changes. You will need to take a combination of medications (under medical supervision) like a proton pump inhibitor such as omeprazole, lansoprazole or pantoprazole empty stomach in the morning and an antacid gel after meals or H-2 blocker such as ranitidine for complete relief. Possibility of H pylori infection too should be looked into by a carbon urea breath test and a combination antibiotic tried. Many a times a persisting H pylori infection can be the cause behind acidity not responding to treatment.
Life style changes that will help include: Drink cold milk. Avoid heavy meals and eat frequent small meals. Avoid too much of caffeine, tea, smoking, fried food and drinks both alcoholic and non alcoholic fuzzy ones. Avoid heavy exercises within 4 hours of a heavy meal. Raise the head end of the bed by pillows to 30 degrees. Avoid lying down for least 2 hours after food. Take a late night snack. Maybe these tips will help you.
If these tips do not help, then liver function test, pancreatic enzymes, and HIDA scan for gall bladder should be done. Food intolerance and inflammatory bowel conditions such as IBS, Crohn’s, celiac etc should be considered. Log in what you eat and see if there is a correlation between a certain food type and the symptoms.
You should consult a gastroenterologist (a specialist who looks after the diseases of our digestive system) or a physician for this.
The other possibility is low vitamin B 12. Take care!
The medical advice given should not be considered a substitute for medical care provided by a doctor who can examine you. The advice may not be completely correct for you as the doctor cannot examine you and does not know your complete medical history. Hence this reply to your post should only be considered as a guiding line and you must consult your doctor at the earliest for your medical problem.
I had the same exact thing happen to me and I became so depressed and hopeless, so just know you're not alone. Doctors can be completely clueless and make you feel like nobody understands or believes you. After a year and a half of horrible throat pain and problems, and doctors performing unnecessary procedures on me (taking out my tonsils, radiating out my ENTIRE thyroid, getting rid of my uvula, scheduling fundoplication surgery for GERD, and almost getting sinus surgery on my nose) I found my savior of a doctor who took me seriously, and was able to correctly identify what was wrong: Vagus nerve dysfunction AND reflux. I totally urge you to reach out to this doctor or at least go on the website and look at her youtube videos/buy her books (ESPECIALLY the chronic cough book, because it talks about the role of the vagus nerve and doesn't only focus on coughs at all.) If you can, schedule an appointment with her because she is a genius and changed my entire life. I am not 100% better yet, but I am well on my way because of her help. If it is vagus nerve pain, you're going to need a prescription for Gabapentin and Amitriptyline for it to get better at all. It helps nerve pain immensely!!!! It is also important to identify trigger foods: things you don’t think are hurting you could be the entire reason your throat is burning! It’s hard to tell when your throat hurts all the time, but pay attention to when it feels worse, what you ate before that, and try cutting out one food you eat at a time for a day or two and see if the pain gets a bit better. Mine ended up being avocados and almond milk!! My throat immediately burns afterward. And if it is just LPR/GERD you're going to follow this diet she has on the website (but explains better in person, or if you can't afford an appointment with her on her videos) that's super strict, but helps soon much with reflux. It's also extremely important to not eat at least 4 hours before bed and don't lay down/recline for 4 hours after you sleep. ALSO: Gaviscon from the UK (not the US version - it's available on amazon) prevents pepsin from coming up at all because the algae in it creates a barrier in your stomach, so I've been taking that before bed and after meals. I HOPE YOU FIGURE IT OUT SOON!!! I know how miserable this is!
Here's the website: http://www.voiceinstituteofnewyork.com/principles-of-dietary-lifestyle-modification-in-the-management-of-airway-reflux-lpr/
The doctor is Jamie Koughman and their office is in NY (but worth the trip! I came all the way from Seattle)