Definitely speak with a personal injury attorney. You may have a case against the child's family, if his or her act was so far beyond what any normal or reasonable child of his or her age would do that it would be considered a wrongful act even for such a child. You may also have a claim against the daycare center if they were negligent, or unreasonably careless, in how they were supervising the children, and that's what allowed the assault to happen. It is worthwhile to consult with experienced counsel about what your recourse might be.