I presume they took biopsies during your colonoscopy? You should be able to chase up the results by phone: the biopsies are what will confirm if the ileitis is Crohn's or not. Although less common than diarrhoea, some folks do have constipation with Crohn's. Being a bit overweight doesn't rule out the possibility either. Not everyone is underweight and malnourished with Crohn's, particularly at the outset.
As for what else ileitis could be, this article goes into that in detail:
/www.ncbi.nlm.nih.gov/pmc/articles/PMC2914216/