Psychologically, it can signify trauma. And it has to be assessed by a psychologist or psychiatrist. Trauma for children can be very insignificant in adults eyes, but something as small as seeing a dead bird on the street can cause psychological trauma in children.
I hope he will get better soon. All the best.
NB: This does not constitute medical advice, please see the disclaimer in my Expert Blog for details.
2. Establish a cut-off time that the child is able to drink liquids.
3. A bell and pad is effective.