I'm so sorry you're going through this.
It sounds like a partial blockage to me. They can happen after any abdominal surgery and are caused by adhesions (scar tissue), so it's probably not the Crohn's coming back.
You should let your gastroenterologist or surgeon know tomorrow, just in case they want to order an X-Ray. If it becomes a full blockage (which is no output with pain and vomiting), go to the Emergency Room right away.
If you keep getting output, but still have pain, your doctor can call in some pain medicine to the pharmacy to give you some comfort.
Take care and please keep us posted on how you're doing.
Dx'd Crohn's in '99 at age 28. Proctocolectomy and permanent ileostomy in '06.
Disease-free and medicine-free since surgery and very thankful to be healthy again.