 The most important I consider is any sudden change in the behavior of the child you notice, that he is now behaving differently what you are used to it and a same feedback can come from the school or the class teacher, the child is now behaving very differently as compared to earlier. Irritability, but the child is getting very angry or irritable, not cooperating with the normal routines which he used to do. And then crying spells, excessive crying spells, stubbornness, refusal to eat food, not sleeping properly, not mixing with the peer group or the kids who wants to go to play and mostly sulking, throwing tantrums.