It's a shame how some pet stores, even one's claiming to specialize iin herps will treat there critters. I hoope she pulls through. With those crowded conditions, it's highly likely she could have a parasite overload. I would get her treated for parasites by a vet or another capable and experienced individual. But if she exhibits otherwise normal tree frog behavior (not laying around on the floor, active and alert etc) I would just watch the color and consistancy of her stools, keep her in a hydration chamber and and feed her a diet that includes wax worms and occassional pink mice just until she fattens up a bit.