Sometimes it can be helpful to try to explore with him how he feels when he is becoming anxious. Try using a feelings thermometer/ruler/rating (e.g., 0-totally relaxed and at ease, 5-melting-down-panic-attack) to get a sense of his level of anxiety under different circumstances. (Google "feelings thermometer" to get an idea of different versions.) The objective is to take away some of the mysteriously-out-of-control dimension of anxiety, by identifying patterns and triggers, and helping him to get a sense of proportion (with some scaling of severity, vs. perceiving every single incident as a total freakout).
He's on the young side for this resource as it is designed, but this is an excellent website aimed at adolescents with mental health concerns (and their families), which might be helpful to those with older children. It includes first-hand accounts of living with anxiety, depression, eating disorders, or schizophrenia, often from mental health professionals, as well as expert summaries of treatments and the current standard of care:
www.copecaredeal.orgThis page connects you to some info/resources on separation anxiety disorder, which usually kicks in in late childhood:
http://www.copecaredeal.org/MZ_Articles.aspx?Condition=1&Article=Separation%20Anxiety%20DisorderHere's a link to the ADAA (Anxiety & Depression Association of America) page regarding children:
http://www.adaa.org/living-with-anxiety/children/childhood-anxiety-disordersIf you haven't already, I would also look into CBT or DBT, which have very good track records with anxiety disorders (right up there with psychotropic meds, actually, for cases of moderate severity).
