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 seizure, severe breathing difficulty, sudden reduced responsiveness, or difficulty waking the child.
These are emergency symptoms whether or not craniosynostosis is present.
Contact the craniofacial team promptly if a child with craniosynostosis develops persistent or worsening headaches, repeated unexplained vomiting, new vision problems, increasing sleepiness, or a clear change in behavior or school performance.
These symptoms have several possible causes but should not be ignored.
Seek prompt advice for fever, increasing redness, drainage, worsening swelling, pain that is not settling, or concern that the wound is opening.
Arrange a routine medical assessment if your baby has an unusual head shape that was present at birth, does not improve with repositioning, or becomes more noticeable.
A hard ridge, increasing facial asymmetry, or slow head growth also needs assessment.
The article also says
After surgery, follow the team's wound-care and swelling instructions.
Every sign above is quoted from the sofidex article on Craniosynostosis. If you are not sure, err upward — it is always reasonable to be checked.