is my sore throat from gastroduodenitis or gerd?

hello there. i was wondering if anyone could suggest me something about my problem. 2 and a half months ago i started having a sore throat which usually feels dry, burning or scratchy. at the same time i started to experience heartburn which i never had before, also cough mostly when i was lying down. otolaryngologist said i have pharyngitis but none of the medication that i tried for it helped and i tried pretty much all the possible stuff. my tounge has also turned white, which he said might be related to stomach problems. so today i went for a gastroendoscopy and i was told that i have a "gastroduodenitis". could my sore throat be becouse of that? and what about heartburn, i read that heartburn is becouse of gerd but when i asked him if have gerd he said i don't, but i've read online that endoscopy isn't really helpfull in diagnosting gerd, so i am very confused. also, very worried about my chronic sore throat which isn't getting better in 2 and a half months now and i don't know why. anyone has any ideas about what's the cause of my sore throat? would really appreciate any ideas.