Hi NGNG,
I agree with imisspopcorn. My first experience with a flare was several years ago, and lord have mercy, the pain, nausea, and vomiting landed me in the ER. The pain was excruciating, slightly above my waist in the stomach area - 10 on a 10 point scale. And mine was only a partial obstruction.
The small intestine is normally about 1" (30-40mm) around, maybe a little more, a little less in places. When I had the flare years ago, my illeum tapered from about 1.5" (32mm) to about 1/4" (12mm) at it's end. When imisspopcorn said it can get small as a speghetti strand, she's totally correct. The inflammation thickened my ileum so there was only 1/4" diameter hole for the food to leave the small intestine. In other words, that's about the diameter of the average ink pen. That's a mighty small hole to try and push a Quarter Pounder and fries through.
Liquid diet for a couple days was the only thing I could tolerate. That worked, and I began slow into eating solids. That whole episode was a turning point in my diet and eating habits. If the ileum would have progressed to total obstruction, they would have to go in for surgery, and probably remove the blocked section of my intestine, or do exploratory to find whatever was causing a total blockage. A full obstruction is very bad news, and you can die from it, so surgery is usually the only option.
So if you have even a partial obstruction, you will be nauseated and vomit, and vomit, and maybe vomit some more. You will have terrible pain that says "Get to the ER NOW or I'm gonna die!" If it's a total obstruction, you will probably undergo emergency surgery. There's also a good chance you'll be constipated too.
I hope that's not where you're at right now.