si problems or just behind developmentally

i just have one question can a 26mo child be delayed across the board except in motor skills and still behave the same for as other kids my daughters age?  her over all age is 16-18mo according to her test in communication,cognition, and social. she is very smart but in the last 5-6mo she has started putting every think in her mouth she never did this, she will spin, jump climb and not stop going until she crashes, she always has to be hugged, and is always giving hugs. at first they said this was si problem but know they say it is because that is where she is in development? is this odd for a child to start such behavior that envolves so many sences and for her to bang her head into the wall if she is upset?

[Kevin Kennedy, Ph.D.]

Dear Jo Hanna,

Some childhood disorders occur after a period of normalcy during early development. Two types of Pervasive Developmental Disorder, Rett's Disorder and Childhood Disintegrative Disorder, for example, follow this sequence.

Your daughter should be evaluated by a team of developmental specialists, including a developmental pediatrician, a developmental psychologist, a child psychiatrist and speech and language and occupational therapists.