Rust will always spread if left untreated, the question is, how quickly? What others have recommended is good. If you're really short on time, you can try cleaning it really well with alcohol and applying several layers of touch-up paint to see how long that holds. Make sure it's dry before painting. I had a couple small spots on my 2001 where I did this, and I never had to re-visit the spots for 12+ years. Keep in mind that it will never be a smaller problem than it is today.