Sudden Repulsion?

I’m not quite sure if this is the right category for such thing, but I have been meaning to get this off my chest, I recently went out with someone who initially did not have such a bad impression(I broke up with this person but that is not the point) but after a week signs started to show. It’s just that I get this disgust this terrible feeling that I can’t rid of, what ever could I do to alleviate it.