If you lay in fast moving water, the water would rush over you. In this case someone or something has affected the writer deeply, like water rushing over them. Water often symbolizes something giving renewal and life; it can also symbolize something powerful, like a fast-moving river.

Backstreet has a song named "rush over me", maybe you can get some help from its lyrics.

"Rush over me" usually means that a feeling hit you very quickly, like a rush of adrenaline or a sense of impending doom.

The previous answers are all good but do you thing you could show us how you first seen it?