What is the word to describe a feeling felt in the past, but forgotten?

I am looking for a word that describes a feeling that I know I felt in the past, but I cannot remember what is was.

I found nostalgia a sentimental longing or wistful affection for the past, typically for a period or place with happy personal associations. But it seems to imply that I kow what I am feeling.

I hope this makes sense and thanks in advance.


Answering your question, I think a nice word is wistfulness characterized by melancholy; longing; yearning. It's pensive, especially in a melancholy way.