Why do I feel like I have to pee right after doing so?

Yesterday and today I noticed that right after I pee, literally immediately, I feel like I have to pee again. I've had many UTIs before, and I know its not that. Usually I can go all day without feeling the need to pee, but all of a sudden I'm going at least 8 times a day. Has this happened to anyone else? If so what did it turn out to be?