HI so sorry for what you are going through. I recently had two root canals and am also experiencing pain and burning in the socket and gums. My xrays look great though and I had an Endo do the work.

Yes there is a significant overfill in your tooth that has extended outside of the Apical area. I read a study where a woman was having pain post root canal and she went all over seeking help. Ended up getting some teeth pulled and her xray showed further up in the jaw remenents of something. They retrieved them to find several file tips and leaked gutta purcha. Once removed all her pain went away.

I think it would be wise to get these pieces removed they dont look to far up in the jaw. The burning moving through your mouth is strange. Maybe if you get the pieces removed and still feel the pain you can investigate a facial nerve issue? I do feel your pain literally