Hi gettingonmynerves,

The x-ray is upside down (this is your lower molar) and very light but it looks like you have a broken file in the distal (back) root. Files are used to remove nerve tissue from the inside of the large canals. This broken piece may also have perforated the apex (root tip). That could explain (in part) the searing pain, heat sensitivity and metallic taste. There is really no easy or predictable way to remove a broken file.

The only option to make the pain stop would be to remove the tooth.

Your dentist should take another look at this xray to determine for certain if the file is broken off in there and he should without a doubt inform you if this is the case.

Bryanna