Running and Muscle Spasms Need Advice

The last 2 times I have run the next day I have a horrible pain in my back between my glutes and spine. It is not a constant pain but very very annoying. Any ideas on how to not get this pain...or get rid of it?

How long have you been running? Have you increased your distance too quickly? Does it feel muscular, neurological, or what?

I've had two lower back injuries and found that the best thing for me was to take time off from running until it was entirely healed. Do something lower impact in the meantime and let your body do its thing.

It seems strange that it doesn't set in until the next day, though. I would think stretching, with particular attention to your back, would help.

I'm agreeing with the stretching thing here. Downward Dog and Cat Pose from Yoga has helped me in the past. Also lay on your back and curl into a little ball with your arms wrapped around your knees and gently rock. If you here a "pop" sound then that may have been the problem. Sciatica or the IT muscles may be to blame.
One other very important consideration is if you are within 2-3 days of starting your period, running will make a bad situation worse. If you have a tendency to back problems (especially if you've had children), then during pre-menses, I would do less impact areobics.