Are you sure the bumps on her side are not her ribs when she is puffing up or that she is not filled with eggs. If the bumps look close to the size of or a little smaller than the size of a marble then she may be gravid. If she was over fed and is obese it is a possibility that she is prolapsing because of being gravid. It happens every once in awhile when a fat female get ready to lay eggs. Although I doubt she was overfed if she came from petco as I ahve been in petco many many times and never seen any food in with anything there. Of course you could be lucky and have a decent person working teh herp department at yours. Once you get better pics of her belly/ butt we will be able to help you figure this out hopefully. A vet is still the best bet though incase it is serious.