This deeply moving canon of prayer eloquently expresses the heart-felt anguish of anyone in need of praying for a sick child.  Includes a full introduction of insightful counsels by a Russian Orthodox Priest-Pediatrician, and the following prayers at the end:  Prayer for a Sick Child, Prayer for a Child Suffering Great Pain, Prayer of Thanksgiving for Healing.

O Lord, show the power of Thy mercy!

What is a Canon?  A canon is a structured hymn used in a number of Orthodox services. It consists of nine odes, sometimes called canticles or songs depending on the translation, based on compositions (also called odes) found in the Bible and, with one exception, the Old Testament.  (Source:  https://orthodoxwiki.org/Canon_(hymn))