My grandson had a seizure initial last week, needed emergency
Not caused by the seizure.
Hello and welcome to HealthcareMagic!
Panayiotopoulos syndrome or seizures in general do not cause such manifestations, do not cause rash. In some cases seizures may manifest with some facial flushing, but that is not itchy and should be easy to distinguish from a rash. So it is not due to seizure. If some medication was started then it might be the cause, otherwise other sources of allergy must be considered.
I remain at your disposal for other questions.