How do i get rid of this contant pain?:(

[Kinjal97]

Before two months ago, swellings started developing on both the side of my tongue.. it was not hurting much but it used to burn sometimes and i couldn't eat spicy food.. it is not my main issue.i don't know if there is any relevance between that and my major complaint
Major complaint:
Soo , at the very back of my tongue it hurts like hell.. i consuled many doctors.. they didn't find any thing wrong.. and they prescribed me antibiotics, antifugel, multivitamin, folic acid medicines .. i took the medicines regularly but my pain was still there..i changed the doctor and he told that it may be stress induced ..so he prescribed  me stress calming tablet.. i completed the dose and there was no result at all yet.. my blood reports are totally normal.. and i am sick of this pain that i suffer from everyday
. Paracitamol didn't affect my pain so I took dyclofinac to reduce the pain(without prescription by any doc).. and there was 20% relief
But i am really confused what to do now.. i feel like doctor can't locate my pain on opening my mouth as it is really very inside .. one ent  specialist told me to go for nasal endoscopy
But my pain is at the back of my tongue
So will nasal endoscopy be relavent for that?
I am really comfused. I don't know what to do. Please help