Hi Sad Mom,
I am sorry to hear about your son and his diagnosis. I know as an adult there are days that is is a rough thing to deal with, I am not sure how I would handle it if one of my boys got this icky stuff.
Certainly I agree with all the other posts, it doesn't sound like it is anything else but Crohn's, especially to those of us that have it. One less dramatic thing to think about is after my colonoscopy in April, about 3 weeks later I had a bleeding episode that looked like I was hemoraging (sp) it was very dramatic and scary. When I called my GI to report it, based on what my scope showed it wasn't anything additional, and sometimes those scopes can be so irritating, that if you have a more solid bowel movemement or a day where you go a few more times than what might have been "normal" for the past few days that bleeding can occur. There are some things additionally in his case that warrant a call to the doctor, but there are some not so scary things to consider as well. Second opinions can never hurt if your "mommy gut" says that you need some additional attention. Best wishes.