This is a hard one because you are providing a good home for it; but are starting far behind the goal line. Well, Petsmart does have a return period and that frog is in pretty bad shape, so that is an option as DVirginiana mentioned. You could keep it and hopefully will improve; but it might have suffered permanent damage to it's internal organs. That happens because they are not receiving proper nourishment during a critical stage in life.
It's probably a Four Spot C. cranwelii and looks a bit like a GA because of malnourishment. GA's hybrids have terrible gene mix and few survive to adulthood; so you do not want that either (even if more valuable). If keeping, get a box of Flukker's Repta Boost. Can dust night crawler pieces with it (can find at Walmart's sports section, get undyed ones). Cut night crawlers from pointy end around the lenght of the frog and offer from tongs by lightly rubbing the frog mouth with piece to elicit a bite. Good luck!