I am by no means an expert at shoes or running, but I've heard a few times that you should be personnaly fitted for your running shoes by a knowledgeable sales person. There are many different brands and many different styles within each brand, and your foot anatomy and running style can make a big difference as to which shoe you should get. I would return the shoes and get fitted for something that works for your foot. You'll probably pay more than you did at Walmart, but if it will keep you from being in pain it will be worth it. Good luck!