I’ve had problems with my mouth and throat burning off and on for decades. Even bottled water can cause it for a week or two so I always bring my own. When I asked my son to buy a certain brand of water to avoid burning, he figured out the high pH waters were okay for me and the low pH ones caused my burning. Those above 7 were okay. That may be true for food too? You might try keeping a food diary to see if certain foods or drinks cause it. Maybe eliminate low pH food and drink for a week or two as a test? You can find pH charts online. Good luck. The burning can be miserable.