She could have gotten them from anywhere. She could have had them since birth, and since before you got her. If going to a vet when there is a potential problem is absolutely not an option, then maybe you should reconsider having her. I'm sorry but anything could happen to animals, and being capable physically and financially to care for them in the event of an emergency should be considered before getting the animal, and this is for more than just snakes too. Fecal exams (without snake being seen) is $25 where I live, if it's positive and the snake has to be seen it's an extra $80 plus the cost of medications. But, that varies.