MAKE SURE THEY DO NOT GET ANOTHER RODENT RIGHT NOW!

The store clearly has a disease outbreak. They should make sure the store knows. The store can quarentine and disinfect until the cows come home and they still won't get everything. Small rodent diseases can go virtually without symptoms until something happens (a move to a new home causing stress). Some diseases are extremely contagious and can pass from various types of rodents and animals with different symptoms with each animal. You can file a complaint with the better business bureau only after you've informed the store that you think they have a disease outbreak and they won't do anything. You'd best make sure its not something the kid is doing that is causing this. A toxic food treat perhaps?