Make sure not too handle the snake after feeding. For two days. Was the mouse fully thawed? Besides that if petco is going to pay for a vet bill,i'd do it. These pet stores I've noticed are really bad at getting healthy animals,or keeping them healthy. They'll sell any sick snake for a dirt cheap price cuz they know its gonna cost them to save it . But yeah I'd go to the vet. Get petco to cover it if u can . You will also need a under tank heater with a thermostat. And maybe a plastic sterlite tub with a locking lid is a better choice. Just read up on this site . And more ppl will reply too.