Several things mimic IBD. If the store sends it for a necropsy (i doubt they will spend the money) you should insist they give you the results. Im sorry your pet died, I understand what these little guys mean to us all.
With that said none of us should ever make a thread/post saying something died of IBD on a whim. Thats one disease that can cause a world of trouble for Herpers.
Clean everything like you mentioned and im sure you'll have fun looking into whats next.