I hate to worry or alarm you by using the term "Autism", but I think you may want to explore that possibility. My son is Autistic, and I have found that most of my assumptions about Autism were incorrect. Autism has a very wide spectrum and a broad scale of severity as well. Also, don't let anyone tell you that Autism is untreatable, incurable or hopeless. I know for a fact (from personal experience) that THERE IS HOPE!!!
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Thank you. I sincerely apologize for my ambiguity, I was seeking advice and greatly appreciate the time you've take to give me yours. I feel greatly relieved to have this added direction.
Based on your statement, even though there is no question, I'm asuming you're seeking some feedback.
There seems to be a combination of factors: possible emotional condition, as well as neurointegrative problem(s).
A clinical evaluation would make sense, in order to determine if your son displays a mood disorder or pervasive developmental disorder (perhaps of a so-called 'high functioning' variety).
In light of his response to stimulation, an occupational therapy evaluation would also make sense, because he may well display sensory integration problems.