Hi,I think you should already have schema name in child.name string.Your child name should be something like:
SHEMA.FEATURE_CLASS_NAME
So all you need to do is split child.name on dot and get first element of the list.
import arcpy
# Create a Describe object
#
desc = arcpy.Describe(r"Database Connections\SDCM_SIS in PRD as 044231 DC.sde")
# Print some Describe Object properties
#
for child in desc.children:
print "\tSchema: %s, Table: %s, DataType: %s " % (child.name.split('.')[0], child.name.split('.')[1], child.dataType)
RegardsArek