Hi Steph and welcome to Healingwell!
My first question is this. How were you diagnosed in the first place? Was it by colonoscopy and biopsy? A biopsy that comes back positive for CD is difficult to contest. Does your new GI have the records from your old GI? If not, you need to make sure he gets them. Diagnosing CD is often putting a lot of puzzle pieces together. I, personally, would not accept IBS as a diagnosis if there was blood in my stool.
Asacol is meant to be a maintenance drug, and to be taken continually. Most of us increase the doseage when we are flaring, and decrease it when we are in remission, but we keep taking it no matter what.
It's possible that your case has been mild enough to be brought under control by the Asacol, then took some time to appear again.
I have never been hospitalized for Crohn's either. Not everybody is.
Get ahold of those old records. Get copies for your new doc and for yourself. Good luck to you.