Having said that, if my son was being victimised or repeatedly hurt by the same child, I would absolutely do what I could to protect him from that, and I get totally why you have that instinct. It's our most important job, to protect our children from harm's way.
Your initial feelings are also one reason why they didn't tell you who the biter was. I have seen parents go little kids over things like this in the initial rush of anger and protectiveness, and carers have a duty of care over *all* children.
Also, I'm not sure if this is right for childcare, but at my school if a student ends up going to the doctor as a result of something that happened on site we have to lodge certain forms with the department, so it would be worth letting them know any follow up that occurs. Maybe someone can clarify?
I hope some of our responses on this thread haven't disheartened you. It's horrible seeing your child hurt - we all understand that x