My sister does not have Crohn's.
My half-sister & half-brother do not have Crohns
My kids are only 3 and 6, and have not been diagnosed with Crohns
My mother was diagnosed with UC within the past year, 22 years after I was diagnosed with Crohn's. She was undergoing a routine colonoscopy, and was not experiencing any UC symptoms prior to (or since) the scope.
We'll keep your son in our thoughts and prayers. Hopefully it is nothing serious.