Removing allergens from your house and diet can be a slow process but it will be an invaluable tool in restoring your child's health.
Allergens can be tested for and removed fairly easily when the allergy tests are thorough, but sometimes you may find a food or other item you suspect triggers your child - either with a physical reaction like redness or hives, or in a behavioral reaction like stimming, crying or aggression.
IgE tests, which measure histamine response (like rash and redness) can be ordered through most any lab for foods and local environmental allergens like pollens specific to your region and are covered by insurance. IgG, which measures delayed or immunological response, can also be ordered but may or may not be covered by insurance. There are specialty labs that run these tests, so ask your functional medicine doctor about them.