The most powerful prayer for the health of the child is the prayer of his mother because the mother is the Goddess who created the body of the baby. It is important to understand that religious prayer is an appeal not to the Creator, but to the god of the religion to which the prayer is addressed. Religion is an egregor with prescribed rules created by people, in which suffering is an essential requirement. So appealing to a religious god with a prayer for the health of the child is not only inappropriate, but also dangerous.
The most powerful prayer for the health of the child is recited by the mother and addressed to the Ancestors.
Put a glass of Water (of course, rain or spring water is better, but whatever you have will work). Fingering the Water in a glass, read a prayer for the health of the child:
«I’m appealing to the beginning of Time and asking the Ancestors for a cover, for a protective cover, a healing cover, a cover that neutralizes all evil. Heal the child of our Kin, Ancestors, heal, make the disease of (name) get out. Get out!»
So read it 9 times.
Then wash the child’s face with this Water.
Prayer for the health of the child will only help and will not make things worse if you do not appeal to religion.