What was the feeling I was overcome with?

I didn't fancy anyone at my school for about 6 months, and suddenly, the weirdest feeling came over as if I liked someone which wasn't to 'pretty' to others. I felt a hurt inside and wanted to be with her , it didn't make any sense. It hit me like a bolt of lightening, and I fought against myself to say I didn't, but I ended up fancying her. I am almost definate it is not love, although I have never felt it.