Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Seek emergency care for severe or worsening abdominal pain with marked swelling, green vomit, inability to pass stool or gas, unusual sleepiness, or signs that the child is seriously unwell.
Contact a healthcare professional promptly for persistent blood in the stool, weight loss, poor growth, fever, repeated vomiting, severe pain, leg weakness, or changes in walking or bladder control.
Symptoms beginning in early infancy also need careful assessment.
A small bright-red streak after a hard stool often comes from a fissure, but heavy or continuing bleeding needs urgent assessment.
Arrange a routine appointment if a child aged 4 or older repeatedly leaks stool.
Assessment is also appropriate for ongoing painful stools, withholding, urinary problems, poor appetite, or constipation that is not improving.
Every sign above is quoted from the sofidex article on Encopresis. If you are not sure, err upward — it is always reasonable to be checked.