I'm so sorry that you had to find your way here because of your son's illness. It is certainly overwhelming to hear this sort of diagnosis but it truly does get easier to accept.
As far as EN, as Clash mentioned, my son did exclusive EN (no other foods) for six weeks, last May-July (2011), when he was diagnosed. He did it through an NG (naso-gastric) tube (inserted it each evening and removed it in the morning). And, as challenging as that sounds, he learned how to do it very, very quickly (a couple of times with the nurse and then on his own after that). After the six weeks, he has continued with EN as a maintenance treatment (1/2 dose, 5 nights per week plus a regular diet added back). He continues to use the tube and it literally takes him seconds to insert. The benefits of using a tube is that there is no bother with drinking 'enough' formula each and every day and no worries about the flavour; the biggest negative, however, is that as all the formula is ingested overnight, there is some hunger during the day/evening. If you have any questions re the tube, just let me know.
But, regardless of the method, it's a great treatment option and it has kept my son in clinical remission (no symptoms) since last year and has reduced/controlled his inflammation TO A POINT... unfortunately, MREs do show some continued inflammation so, most likely, we will be facing medications soon.
As far as supporting him with Modulen, the challenges are a bit different from having the formula overnight... my son was allowed clear fluids, broth, jello, etc. during the 'exclusive' EN period, this helped him a bit. When feeling hungry, distraction helped. In my son's case, I didn't give him the 'final' date of the formula (until the very last week) as I thought it might be overwhelming to know there were 'still 5 weeks left', 'still 4 weeks left', etc. However, everyone's different and I know some parents have said it helped their kids to count down the days...
Just a note, while I believe drinking the Modulen 'cold' is more tolerable/palatable, I have read that 'freezing' it into popsicles, etc. can cause the formula to lose some of its nutritional value.
I don't think anyone will be able to give you a definitive answer as to whether things will worsen. People respond differently to treatments, have different symptoms, react differently to diets, etc. Some have to try various treatment options to find the right one and others find their right treatments right away.
There is tons of information on this forum and lots of wonderful members who will share their knowledge! Ask questions!! And, have a look through the Enteral Nutrition and AZA treatment forums and the Supplements, Diet subforum.
Also, please come to the Parents of Kids with IBD forum (lots of of great, great parents who understand your worries and are always there to support you!).
Here is a link to the Kids' Success Stories thread... it may help to read of kids who have done well so far!
http://www.crohnsforum.com/showthread.php?t=27079
Good luck!! :ghug: Please let us know how your son is doing!!