I'm also so sorry your little boy is sick with this disease.
I suggest you get him on some children's probiotics (Udo's is a good one). A probiotic is best when there are several strains of organisms as in Udo's.
I also suggest you prepare mostly natural foods for him. Cut out processed food and sugar; these are major aggravators for us with CD.
I agree with getting him to see a pediatrician that specializes in crohn's.
I sure hope he'll get better soon.