I also had that trouble. I found a website about sports injuries. THe good thing about IT is that you don't have to stay off the bike. Just take shorter rides, ride in a lower gear and don't do hills for a while until it feels better. It's just from overtraining. Running may aggravate it, though.
Another stretch: lie on your back, and pull your left knee across your body, not straight across but toward your shoulder,with your leg bent. Hold the stretch and feel your hip really stretch. Do the same with your other leg. This stretches the hip which keeps the IT band from getting tight.
You can catch more flies with honey than with vinegar. That's great...if you want to attract vermin.