So over the past month or so, I have been training to run a 5K at the end of August. I have never run a race that long before but the training has been going well in my opinion. When I started I couldn't even get past a quarter mile without having to slow down...but now I am up a 27 minute run at around 2.5 miles. But here's where it gets sticky. I just started bumping my time over 20 minutes about a week ago but now my lower back is starting to hurt. I stretch like crazy before and after the run, and even in the morning when I wake up and at night before I sleep. I pulled my hamstring in January, so I won't to make sure I am warm before any workouts. It's annoying now because I can feel my back tightening up but I'm not sure what more I can do to make sure it's loose before my workouts.

Any suggestions?

Impossible to diagnose over the net, but do you do any resistance training?

Here's my usual workout: http://www.joeylosesweight.com/image...es/workout.JPG

I've switched the amount of strength workouts with the days I run, so I run 3x a week and do this workout 2x a week