Hello and hope you are doing well.
The common causes for difficulty in swallowing are enlarged tonsils and GERD. Gastro esophageal Reflux Disease (GERD) is caused due to reflux of acid from the stomach into the esophagus. It can also happen due to iron deficiency anaemia causing Plummer-Vinson syndrome, where there changes to the soft lining of the throat. Since GERD has been ruled out, consultation with an ENT specialist may help rule out other causes.
Hope this helped and do keep us posted.
I've had what seems to be this same thing for over a ******* year now \it's horrible and I don't feel comfortable anywhere I go anymore, I feel I've become anti-social and depressed because of it, and its ruining my life.. I wouldn't wish this on my worst enemy.. I was at first diagnosed with a little bit of GERD or acid reflux, I am also thinking It's not that.. I got the gastroscopy done and everything is good apparently. I was just talking with my parents and my mom suggested taking an anxiety pill which I'm hoping will work, hey there's nothing to lose.. anyway I hope you find a cure. (This happened about 2 weeks after getting my braces off) don't know if that is a factor leading to this...