It's easy to be tempted to stick to your schedule, because that's what you want to do. But I think you should listen to your body, and if it's telling you rest is more important, then I would listen to those signals. Here's an article you might find helpful: www.sparkpeople.com/resource/fitness_artic
It might just be a one day thing, so try a day of rest and see if you feel better tomorrow. Continuing to push through might end up making the problem worse.
Hope that helps,