What the hell is wrong with my cat?

Lately she has been like super jumpy, and she's never been like this before. For example, I was taking out the trash before and I was walking into the bathroom to get the garbage out of there, I didn't know she was laying in there and all of a sudden she comes bolting out hissing and skidding all over the floor. Now for the record, i barely even made any noise. That's just one example, there's been more times like that, she's just super super jumpy which is not normal for her. Is there anything that could have happened to make her this way, besides something simple spooking her? because it's been going on for a week or two now, so i think it was more than just something scaring her...