food sensitivities , including foods and drinks high in phenols. The child may benefit from support for sulfate that is involved in breakdown of phenols, natural adrenaline, etc.
Adrenal *cortex* support such as cortex glandular.
Heavy metal detox.
Autism Research Institute treatment parent ratings 2009 http://www.autism.com/index.php/treatment_ratings_asd
"Detox. (chelation)" 74% report "got better", 3% report "got worse", 23% report "no effect"
The 74% rating is the best of the many dozens of listed interventions.