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 a first seizure, a seizure lasting several minutes, repeated seizures without recovery, trouble breathing, severe injury, sudden one-sided weakness, or a child who is difficult to wake.
Contact the child's clinician promptly if there is a clear new loss of language, movement, awareness, bladder or bowel control, or self-care skills.
Prompt assessment is also appropriate for staring spells, repeated unusual movements, major changes in walking, persistent headaches, new weakness, or a rapid change in behavior.
Fever with marked confusion, neck stiffness, or rapidly worsening neurological symptoms also requires urgent assessment.
Routine follow-up should review development, communication, learning, behavior, sleep, nutrition, bowel habits, hearing, and school progress.
The care plan should change as the child grows.
Transitions into school, adolescence, and adult services often require early planning.
Routine developmental concerns without sudden deterioration can usually be discussed with the child's primary care clinician.
Families do not need to wait for a completed autism evaluation before requesting early intervention or a school-based assessment.
Every sign above is quoted from the sofidex article on Autism spectrum disorder - childhood disintegrative disorder. If you are not sure, err upward — it is always reasonable to be checked.