Claudia,
I am so sorry your little Louis has to go through this
It is not your fault. Those nylon bones say their safe, however, not always. Is the vet certain that this pieice is not too big for him to pass?
I am just thinking he is uncomfortable right now, however, I'd be scared of an obstruction ? But if the vet says he is ok , then I am certain he is fine. Follow the vet's instructions, and I will be praying for your baby.