With these symptoms, should I consider that it is gastroenteritis? Another infection or childhood illness?

With those symptoms, it is possible that it could be gastroenteritis, another infection, or a childhood illness. It is important to monitor your child's ability to eat and drink properly. If the fever persists without an apparent cause, it is recommended to consult a healthcare professional. It is also advisable to seek medical advice if the child has been experiencing a fever for 72 hours without improvement.