Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
1
Is any of this happening now?
Call 911
These usually need timely assessment but are not automatically emergencies.
Go to an emergency department or call local emergency services if your child has:
Severe or rapidly worsening abdominal pain
Trouble breathing, blue or grey skin, or chest pain
Fainting, confusion, extreme sleepiness, or difficulty waking
Repeated vomiting with an inability to keep fluids down
Signs of major dehydration, such as very little urine or a very dry mouth
Vomit containing blood or material that looks like coffee grounds
Other emergency signs, for anyone
Someone who is struggling to breathe, gasping, choking, or cannot get words out
Someone who has chest pain, tightness or pressure lasting more than a few minutes
Someone who has sudden weakness or drooping on one side of the face or body, slurred speech, or sudden confusion
Someone who is unconscious, or cannot be woken
Someone who is bleeding heavily and it will not stop with firm pressure
Someone who has had a seizure that will not stop, or does not wake up afterwards
Someone who has lips or skin that look pale, blue, grey or blotchy
Someone who you believe has taken an overdose or swallowed something poisonous
2
Is any of this happening?
Be seen today
Seek prompt medical advice if your child has persistent or repeated upper abdominal pain, especially with vomiting, poor eating, fever, or pain spreading to the back.
A child with known pancreatitis should also be assessed if familiar symptoms return.
If a significant blow to the upper abdomen is followed by worsening pain or vomiting, urgent assessment is also appropriate.
Pancreatic injury may not be obvious immediately after an accident.
The article also says
Contact the child's usual care team soon if there are signs of longer-term problems, such as greasy stools, poor growth, weight loss, repeated pain, increased thirst, or frequent urination.
Every sign above is quoted from the sofidex article on Pancreatitis - children. If you are not sure, err upward — it is always reasonable to be checked.