I would agree with Portia. That level of sensory-seeking at the age he was 1.5 years ago and at his current age are quite different in significance. The behaviors around food are also a bit beyond both sensory-seeking and GT-related sensory overexcitabilities, and would, in particular, suggest that a comprehensive evaluation, covering a broader range of aspects of development than sensory, ADHD, and GT only, may be advisable. You may wish to consult with your child's primary care physician regarding a comprehensive neuropsychological evaluation, in coordination with OT evaluation. (Such an evaluation would include the GT testing that you were already considering, but within a much richer context regarding his overall development.)
