I’ve had this twice before after longer fasts and I’ve seen it mentioned in this sub. Mine feels like it’s swollen and sore, really hurts to eat anything but does fade over a few days. I think (from what I’ve seen on here) it’s linked to dehydration whilst fasting, but obviously I don’t know for sure. Try soup, or really cold milkshakes/thickshakes.. those were the least painful things for me. Make sure you keep drinking plenty too!
Maybe try brushing your teeth an hours before breaking? I think that roof of mouth burning is related to bacteria in the mouth. Genuinely can’t remember where I heard this. Maybe a PA but not dentist. Worth a shot though.
I’ve found that I have to eat small amounts very slowly to avoid this. It’s often difficult to eat slowly when refeeding but if I take very small bites and chew slowly I avoid this. My routine is to drink some broth, take a bite of an olive, chew slowly and swallow, then drink a small amount of broth. Then I take a small spoonful of greek yogurt or sour cream or something like that to follow up. I just do that spread out over about 30 -45 min. Then I wait a couple hours and have my real refeed meal and I seem to be able avoid that burning swollen throat episode.