How do I describe a bad memory or flashback?
For example, when I've had a bad experience, and I'm in the same situation again (sort of like a negative déjà vu), I could say:
Forcing myself to concentrate, I tried to ignore the *insert phrase here*.
Best Answer
A metaphorical expression used quite often hereabouts is ghost of the past.
The Urban Dictionary definition is fine here:
The related lay the ghost of something (to rest) is relevant:
[CDO]