URL injection file in cache

Hi guys,
So search console says I might be hacked via URL injection. The example pages given return 404.

While doing some digging via Filezilla I noticed a file in my hummingbird cache called Work. Opening that leads to essay>hiv>aids. That is one of the offending files.

While I can find the file in the cache, I can’t find reference anywhere else. Is it possible to see where hummingbird found that file to cache? I’m just looking for clues that lead to the root problem.