Son has a peanut allergy. with no exposure to peanuts he has broken out n hives with diarrhea 4 3 days. should we have him allergy tstd 4 everything?

Yes: Having one allergy can make it more likely to have other allergies. It would be a good idea to have him seen by an allergist and tested to see to what else he might be allergic. Though allergic children tend to have multiple allergies, being allergic to more than 3-4 non-cross reacting foods is rare. History is primary, skin test confirmatory. Consult an allergist for diagnosis and management.

Perhaps: Acute hives may be due to drug or food allergy or to viral infection. Hives & diarrhea may indicate an infection. 40% of peanut-allergic children are also tree nut allergic. Did he eat a tree nut? Could he have eaten a food contaminated with peanut - say a food prepared in a plant where peanut is also processed? Write down everything he ate in the 24 hours before hives & discuss with his allergist.