I totally agree with what's been said about good shoes. Let me add that it's important that they're not only good shoes, but the right shoes in the right size for you and your biomechanics.
I started off in Asics, which are great shoes. The issue wasn't that the Asics weren't good shoes, it's that they weren't suited to my wide feet, high arches, and underpronation. What made things worse was that I ordered them off the internet. In the size I wear in regular shoes. Without having my feet measured at the end of the day. One week before a race.
D'oh!
Many podiatrists visits and a pair of $400 orthotics later, I've learned the value of specialty running stores and why people pay $150 for the right pair of running shoes. I got the right shoes for me now and I'm running pain free.
My advice would be: Go to a specialty running store ( not Foot Locker or Dick's ) after you've on your feet all day. Bring your old pair so they can examine the wear pattern. Give yourself plenty of time so you can try on several pairs. Don't be surprised if they tell you to get a 1/2 to a whole size bigger than you normally wear. Take them for a test run around the parking lot. Good stores will let you bring them back ( within a certain time frame ) if they make you hurt when you run.
Something else to consider when you have running related pain is where you might have weak muscles. Anytime one muscle in the chain is weak, another has to take up the slack. Strengthening your abs and glutes usually helps take stress off your back.
Hope this helps!