If your toddler’s sunny demeanor suddenly has a storm cloud, then there could be a hint that their brain has sustained an injury. The Mayo Clinic says your little one may not seem as engaged in activities or playing with toys, which is essentially the younger version of depression.
They may become quieter and mope around in a sad way. On the flipside, your happy child may cry persistently and you might not be able to console them they way you did in the past, adds the source. Other sources say a child with a TBI might become more irritable and short-tempered.